Google
Every time I googled an agent who requested a sample of the book I was working on, I would get this site in my list of results and I could get instant feedback on who was who and what they were all about. After browsing around for a couple of months, I finally decided to join, mainly to meet other writers who are going through the process. After graduation, I realized that where I live is a bit of a creative "dead zone," or at least there are very limited outlets of creativity. The people who post to this board sound like a creative, intelligent, well-spoken bunch.