Don't sue them...toy with them. Waste their time. Make them call you back, put them on hold, string them along, then disappear. Like car salesmen, unethical recruiters have a high tolerance for rude behavior. The only way that you make an impact is by hurting their paycheck.

(I used to date a recruiter who did cold calls like this. She could handle any type of rejection, but she hated it when a candidate played her. Every time she would rant about it, my faith in the world was restored.)