If you love mid-century design as much as I do, you'll surely love LushPad.com, an online marketplace for buyers and sellers. Lushpad takes the CraigsList idea to a new level with advanced search options that help you narrow the search results. If you don't find what you're looking for, you can setup an Item Alert and receive an email when the piece becomes available on the website.
Aside from the furniture posts, you can also read the Trends blog or catch-up on history with a few biographies on mid-century designers.
I'm on the lookout for a new desk and a vanity for my bedroom. I hope one shows up soon!