The PDC 2003 Online Sessions are just great. I was learning stuff by watching the various sessions while I was cleaning up my harddisk. Sure there are some marketing hyper during the sessions, but at least they provide some technical information that is beneficial to me in long run.

I just hope that Java community has something similar.

I particularly enjoy the session which tells me some pitfall and bug of the current framework, with introduction to some tools that can help me to dignose a .Net application. Here's the list. I have a feeling that I will use some of the following tools/links very soon.

BCL Site (String, DateTime, Breaking Changes)
http://www.gotdotnot.com/team/clr/bcl/

Design Guidelines:
http://www.gotdotnet.com/team/libraries

FxCop:
http://www.gotdotnet.com/team/fxcop/

CDP Info:
http://blogs.gotdotnet.com/anathan

CLR Profiler and CLR Performance
http://gotdotnet.com/team/clr/about_clr_performance.aspx