There has been many posts asking how you should bring your spending money to LOS.
Cash, Travelers Cheques, ATM card or Credit Card. If you're Australian like me, your banks will screw you big time on the last two in that list.
I got hit with almost 5000 Baht in bank charges my first trip. Foreign transaction fees, ATM fees, the list goes on...
On my last trip I set up a Thai Foreign bank account with Kasikorn Bank (Farmers Bank) and it was the smartest thing I have done on any trip.
The process is simple...
You arrive at a branch (listed below) with your passport, hotel card or number for condo owner and 500 Baht (One time payment).
I used the one on Beach Road near Soi 5.
Beach Road Branch Map
Pattaya Klang Branch
Pattaya Klang Branch Map
Royal Garden Plaza Branch
Royal Garden Plaza Branch Map
There is also a new one that's not on the list in the new Central Festival Plaza (4th floor I think).
You simply walk in and ask for a Foreign Bank account.
A normal Thai bank account will require a work visa.
They will asked for your passport and number where they can confirm you are staying.
After filling in the paper work, they ask how much you wish to deposit and you hand over your funds.
This was counted at the desk and then taken to the Exchange booth just outside the branch.
So no exchange fees on that either.
Once brought back they counted the Thai Baht again to confirm the amount.
They get your e-mail address so you access your online banking.
After the deposit was done, I was given an ATM card and the cute little Thai teller took me outside and she asked me to put in a new PIN number for the card.
... and that was it. Done in 15 minutes.
I now had access to my holiday spending in Thai Baht.
I have zero account management fees.
I have zero ATM charges.
.. I have even earned 7 Baht interest on the 500 Baht I had left over. 
So from now on I will arrive with cash in my pocket and deposit it immediately into my K-Bank for my spending money for the duration of my stay.
I'll bring a credit card for emergencies and that will be left in my room safe.
I would advise against using the online banking from Australia.
As the banks here will lay enough charges on the transaction and to make the exercise pointless.
One final point.
Their ATM's are EVERYWHERE.
Soi Buhkao
Soi Buhkao ATM Map
Soi Diana
Soi Diana ATM Map
Mike's
Mike's ATM Map
There is one opposite the entrance to Pattaya Beer Garden near Walking St, Pattaya Klang, Walking Street...
You can't seem to walk 100 yards in any direction in Pattaya without seeing one.
I will mention I had my card eaten by an ATM one morning and I had the card back by 6PM that night.
Myself and two of my friends in Brisbane use this system as well.
For me personally, as I am disgusted at how the banks are screwing us these days, it is the simplest and cheapest option out there.
Be aware that Thai Customs Officers will not be happy if you try to bring in more than $10,000 US in cash undeclared.
How you declare more than 10,000 is something you will have to find out yourself... sorry. 
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UPDATE - NOV 2012
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For those of you that want to exchange for Thai Baht or already have a K-Bank account I would highly recommend paying a visit to the Suvarnabhumi K-Bank Exchange/ATM rather than the exchange near King Power at customs.
The exchange rate is superior to the one at customs. There are plans for a full branch at the airport but it does not as yet exist.
The Exchange and ATM can be found on Basement Level 2 just at the entrance to the train station. Just follow the 'Train' signs and you can't miss it.
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Bangkok - 2013
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Most of us stay around Nana or Cowboy. So on my last trip I hunted down a few ATM's and the K-Bank branch on Sukhumvit.
There is an Exchange and ATM beside the Landmark Hotel towards Cowboy.
There also appears to be a branch inside the building beside it.
There is a pedestrian bridge close to the Landmark Hotel, in between Nana and Cowboy, and this will get you to the branch closest to both.
It is located close to the corner of Sukhumvit and Soi 15.
It is a small branch that you should be able to set up an account in.
I wait for replies to see if that is the case.
*Be aware that if you set up an account here, anytime you use the account outside Bangkok you will incur a 15 Baht fee*
There is a ATM in Sukhumvit Soi 11 north of Sukhumvit...
...and another south of Nana plaza about 100 meters down Sukhumvit 4, outside Hillary 2
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FAQ
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I just went through 30 odd pages and grabbed the most common questions.
This will save you guys hunting for info.
My thanks to Serpentine for adding this to the OP.
Common Questions
#1
Any knowledge about branches in Bangkok being as accommodating as those in Pattaya?
The BKK branches are not as accommodating as Pattaya from what has been reported in this thread.
You may get multiple 'No Habs'(No have) before you finally manage to get your account started.
There are also reports of the Thai's asking for a work visa before opening these accounts.
Another 'No Hab' and is NOT required. 
#2
Do you have internet access to your bank at home?
K-Bank will ask you for your e-mail address as part of the application.
So you can access your account from anywhere in the world.
YES... you can transfer money over the Net.
But the banks, especially in Australia, give piss poor exchange rates unless you send Australian dollars to be exchanged at K-Bank in LOS.
#3
Is there a limit or what is the daily limit on withdrawals from K bank?
- Maximum daily withdrawal at KBank branches is up to 2,000,000 Baht with presentation of your savings deposit passbook and national ID card.
- Maximum daily withdrawal at an ATM is 200,000 Baht.
But ALL Thai ATM's have a transaction limit of 20K Baht withdrawal per transaction.
Any foreign card used in an ATM will incur a 150 Bt fee... PLUS whatever your bank charges.
K-Bank has six or seven regional districts. If you use your K-Bank card in another district you will be charged a fee.
From the K-Bank website...
No fee for withdrawals within the same clearing district
Baht 10 for every Baht 10,000 withdrawal across other clearing districts (a minimum charge of Baht 10 per transaction)
The 10 Baht fee is nominal so I don't worry about it.
It beats the hell out of 150 baht per transcation and whatever your home bank charges you.
But it does pay to get an account close to where you plan to stay the most.
#4
Do you know what interest rate Kasikorn is giving you?
Between 1 -.1.25% currently
#5
How long does it take to transfer money to LOS?
Around 3-5 working days is the general consensus.
#6
Is there is a monthly service fee?
No fees. But there are stories of a 500 Bt yearly fee.
In any case it's still the cheapest option out there.
K-Bank started a policy August 2nd 2010 to get rid of the unused accounts.
From the K-Bank website...
Baht 50 per month for an account inactive for more than one year, with outstanding balance of less than Baht 2,000
Baht 100 per month in cases where an account has been inactive for more than one month, with an average outstanding balance per month of less than Baht 1,000
#7
How long can you keep the account open for ? is it just for the duration of your stay ?
As long as you have a balance you will have an account.
#8
How much money can I bring into the country?
$10,000 US is the current limit undeclared.
I'm not sure how you go about declaring anything in excess of 10k and no responses have indicated what is involved.
#9
How do I recieve a statement?
All statements/balances etc are accessed online.
You can ask for statements to be emailed to you here.
https://rt07.kasikor...initLanguage=EN
News and updates are sent via e-mail.
#10
There are kasikorn branches everywhere right?
Kasikorn bank is the Farmers Bank.
They are just about everywhere in Thailand.
If you have a problem finding one just go to the local mini-mart, pull out your card and point to it.
The service clerk will normally send you in the right direction.
#11
What hours are banks open in Pattaya?
It varies. But some are open 7 days a week from around 10am till around 8pm.
#12
Did you exchange your dollars at K-Currency Exchange place first or can you deposit straight into bank?
I walk in and sit at one of the desks with the cute service girls and hand the money over.
They handle it from there and I see the exchange rate on the receipt.
#13
Do they give you a SWIFT code so you can transfer money from your Falang account into your Thai bank account online?
Yes. But ask for it if they do not provide it.
#14
What about transferring money yourself on the net from your Aussie Acc to your Thai K Acc, I thought there was no fee?
$20-$30 (600- 900 Baht) transfer fee on most Australian banks and/or Foreign exchange fees and piss poor exchange rate. I'll take cash. 
K-Bank also have a service to recharge your Thai phone sims on their website.
Very handy.
...And FINALLY... the great debate.
If you are uncomfortable carrying cash around, use travellers cheques.
They get a slightly better exchange rate and may possibly cover the cost of the bank fees they incur.
If you get them for nothing, all the better.
Have a great trip. 