[Air-L] Reliable "academic" online research panel company

Hi! All, Please help me to find some good online research panel firms based in US. I mean reliable and cost-effective by saying good (: I have been looking for them, but my search has not been productive. If possible, I would like know more academic-oriented firms than market research panels. Some of them may do both. I would be grateful for your sharing of experience and information. You can email me at kyun4zzing@gmail.com. Thank you for your inputs in advance. Kyun Soo