A reader recently asked what TabletPC resources I recommended. Instead of replying to him directly, I figured I'd share these resources with everyone else too.
My favorite and one of the best sites is Tablet PC Buzz, run by a couple of MVPs: Spencer Goad, Rob Bushway and WNewquay (who insists he doesn't actually "run" TabletPCBuzz). Subscribe to their blogs too. The members here are very helpful and extremely knowledgable. I've been a member since the summer of 2003; the Buzz guided me on both Tablet purchases.
Lora and Loren (what sadistic parents) are responsible for Tablet PC Post, a site that brings a lot of Tablet PC software under one roof. I don't visit the WhatIsNew forums nearly as much as I would like; they are also a great resource. Also, see Scott's list of great tools for your Tablet PC.
Unfortunately, I haven't had time to do a lot of actual Tablet development, but the Tablet PC Developer Center is probably the best place to start.
This is what comes to mind initially. I'll try to add to the list as I remember. Anyone else have anything to add?