Going to add a couple of links to sites I enjoy. The first is to an online trading forum called The Bench. The site has over 5,000 members and yet is very comfortable. Pete, the owner, and his team of moderators do an excellent job and keep things under control. The trade manager feature is extremely nice as well. If you want to give online trading a shot and haven't tried The Bench yet you really ought to. Tell them Spiff sent you.
Second site is another card blog that I have enjoyed called Squeezeplay Cards. Joey collects more than just baseball and writes in a way that is very enjoyable. He has a few players he focuses on but overall just talks about cards in general.