I'd have to say that my weakest area of development is probably SharePoint. I know how to build a basic SharePoint web part and that's about it. I'm pretty much a dunce when it comes to SharePoint. One of the things I've been telling myself for the last couple years is that I need to bite the bullet and "get smart" on SharePoint development. For the first time in a long time, I have some down time so I am going to try to block of some time in the coming weeks to do so. Where to start? Paul Andrew blogged about a series of 10 MSDN webcasts covering SharePoint for .NET Developers. All of the webcasts were recorded:
There is also a fairly new resource for SharePoint development at http://MSSharePointDeveloper.com. These resources are where I am going to start!