TM7 form, 4x6 photo, copies of passport page, entry stamp and departure card and 1900 baht in cash. If you dont want to do it yourself G4T upstairs at Prom can do it for an extra charge.
A small overstay absolutely doesn't affect future visas - at least in my own experience. 1 day and 6 day overstays (the last one due to immigration baa mak mak) and never been called up because of it. Had an SETV and ED since.
also @luke not sure where you are from, but for commonwealth citizens it's 90 days free visa exempt stamp into Malaysia, I think other westerners get 30 days free.
@luke link below. Ive used him once based on recommendations by others, March this year, couldnt be more simple. Make sure you take "proof" of a flight out of Thailand and accomodation details - Penang consulate requires it now.
k and thanks for the reply. Flight cost - Penang or KL will probably be your best cost wise. Penang would be my personal recommendation - really nice place, if you want a tourist visa you can pay an agent to do it for you for and not a lot of money. Stay on Chulia Road, hire one (Ive used Jim's before but it's up to you) and while I like KL as well, Penang is cheaper.
Maybe he's in Hat Yai, maybe Udon Thani, maybe Chiang Mai, or maybe you're a dopey [redacted] that thinks that Bangkok is the only place in Thailand perhaps :)