Here's a good opportunity, guys. I've been bragging to the guys over at chineseteachers.com about how great you all are at giving feedback, and they're offering beta invites through this forum. They've just started their beta and you'll be among the first users, but I think the site is already very useful because...
They're paying hundreds of Chinese teachers for one-on-one lessons for you to test it out. So they can't do a fully open beta, but the first 25 people to register via this link will get $20 of credit with which to test the site and also find some good teachers:
http://www.chineseteachers.com/entrance?id=c364850220644e30012066f3840c0008
Depending on the teacher's experience, that's up to an hour of lessons, so check it out. They charge by the second, too, which I think is a great idea, and with the number of teachers they've signed up, lessons can fit your preference and your schedule. The site works by matching you up with teachers and then providing a Skype-like audio widget embedded in the site, so they take care of all the infrastructure.
Anyway, if you do sign up, please do give feedback--they respond quickly and need your help. It's a small beta, so don't assume anything has already been pointed out.