DJs, SJ Radio Shows and other SJ-specific cats - An extension of Kevin "Slow Jammin" James's original radio show called, you guessed it, Slow Jam.
Slow Jams Radio - Want to hear slow jams online 24 hours a day?  Want to catch the Sunday Nite Slow Jam show by R Dub, as well as a few other choice slow jamming DJs, or to see if it's on a radio station in your area?  This is your site!

Wrecka Stowes
Dusty Groove - Probably the most extensive rare R&B/soul/funk collection of any easily accessible record store, and mostly in new or good condition. CDs and vinyl and more, with great service online. They're based in Chicago, so if you're ever in the area plan to block out about 2 hours of your day to shop.
Amazon - Lots of nooks and crannies and imports, and their used prices are to die for.