1. Document everything. Print out all communication.
2. Resign in writing, print out the email you sent.
3. File an unpaid wage claim for any salary they refuse to pay.
4. Get a new job.
They won't get anywhere trying to sue you. You, on the other hand, will have a much easier time collecting unpaid wages. Google "unpaid wage claim" for your state.
Please note: I am not a lawyer. This is not legal advice.
Best answer on yahoo says you can sue: http://answers.yahoo.com/question/index?qid=20090705044359AA... This website has advice from a lawyer about what to do: http://lifehacker.com/5993754/what-should-i-do-if-my-employe...
However, please talk to a lawyer in your area about this. My post is meant to do nothing other than encourage you to find out your rights and the practicalities of the situation and take care of yourself.
Keep in mind that in many places, your employer is in serious trouble with the Labor Department or equivalent if he does not pay you. Any legal action to obtain the salary in lieu, even if successful in collecting it, would be wiped out by fees, fines from the DoL and his obligation to pay you.
What country is this?
Check your contract, if you don't have one they don't have anything on you. If you do have one, check conditions. Just because they aren't playing ball with your pay, doesn't mean you can just leave.
In all cases, send them a written letter giving your notice (in sickly nice pen) and count down the days.
I would get out of there asap. You are essentially providing them financial credit (unwillingly). When a debtor doesnt pay, typically you cut off the credit or increase the interest.