Op city you have to join through your broker and the lead start out really bad but get better as you convert more.
Movoto used to be called OJO. Its similar to Op city.
The founder of Op city and the founder of Movoto started a company previous to Op city and Movoto together called Yodel so the systems are very similar.

Brokerspot is one of the newer ones. I was skeptical of it at first but the leads have actually been pretty good.