The Microsoft Webcasts Series page is pretty good in giving a broad overview of whats available, but it is by no means complete.
I got the following links from George for the Modern Software Development series.
Modern Software Development in .NET and C# to start on March 1 2005
Modern Software Development in VB.NET – Previously held live and recoded Jan – April 2004
I think they should collate all the series into that page so people can always get to them especially when multi-part webcasts are involved. The Blog community could do this, but it wouldnt be the same as having it all in one place.
For our internal knowledge portal I have collated all the BizTalk webcasts so that people have a one page overview of whats available (whether they then go and view them is another thing altogether).
Just found some good posts (part 1 and part 2) on Joe Wood's blog dealing with mapping XML Schemas to classes and responded to part 2 also. Check them out.