I am relocating to China in February and have several job offers. Deciding where to live is the biggest decision - there are thousands of jobs there and they're easy to find. If you have the qualifications to work for a university (Bachelor degree only at some, M.A. + TEFL/ESL cert/diploma for others), forget using agents. I would suggest you read this forum fully and check out the forum on Dave's ESL Cafe also if you really want to use an agent: http://www.eslcafe.com/forums/job/index.php
University jobs are far better than jobs at language schools. Try these sights for job contacts:
http://www.chinatefl.com/
http://www.abroadchina.org/person/all.asp
http://www.tesol.net/getjob.cgi?FA=ListJobs
GOOD LUCK!