You could try the online job pages for The Nation and Bangkok Post, I think you can search by sector if you don't wanna look thru all the jobs. They're nothing like the job resource that ajarn.com offers for teachers, but occassionally there are a few gems, especially from hotels.
There's also thailandteacher.com, which I understand is under new ownership, I had a look the other day and whilst there are not too many jobs right now I do like the page set out, easy to follow, and given that the advertising of jobs is free I'm sure it will be a useful resource for the job hunter in the near future - certainly one to keep your eye on.
If you're after work with language schools the quickest way is prob just to visit their websites, they'll always take on bods with good solid creds. Same with schools, come january I think they will have press gangs roaming BKK.
There's shit loads of other websites offering tefl jobs, but not specifically for Thailand, although you can do country searches, try eslemployment.com, eslpro.com, esljobs.com, huntesl.com, esljunction.com etc. etc.
I check out all sorts of sites, just to make sure I'm not missing something, but I do tend to make ajarn.com my first port of call, right now I don't think you will find a better site.