Update 11/1: Pinecone Research’s Open Recruitment Week has ended but Opinion Outpost  is a great alternative that I’ve used.
I wrote about Pinecone Research (and Opinion Outpost) a little while back and I wanted to let you know that the open enrollment period has started again. Visit Pinecone Research  and click on the scrolling marquee at the bottom, titled Open Recruitment Week – click here to signup for the panel! I don’t think there’s any other way of getting to it directly.
For some of my thought about Pinecone, read this post titled “Pinecone & GoZing – Two Good Survey Networks “.