We use the Picture Exchange Program. Emma does sign, but she has begun to use this at school and we are reinforcing it at home. It has helped. Emma is not potty trained, but we follow the same procedure that school does. However, we don't try all day long...only before bath time. She has to site on her potty until I count to ten. Then we put her in the bath tub. She has only gone twice and we have been doing this since May. She does tell us when she is poopy, but that just started in the last few months.
Emma's Homepage:
http://homepage.mac.com/lsnowbarger/peanut/Menu60.html
Family Blog
http://snowbarger.blogspot.com/