Microsoft just released a toolkit that greatly simplifies deploying MSDE with your .NET applications. I guess this will have to hold us over until WinFS comes along and gives us a built-in database.
GotDotNet has posted a P/Invoke Cheat Sheet. They have a collection of articles how to use P/Invoke and, best of all, a library of P/Invoke method signatures and structures for the Win32 API.
Here's a handy article entitled "Making Sense of ASP.NET Paths". It's a good reference if you find yourself trying (and failing) to generate absolute URLs to other ASP.NET pages on your site.