A couple of highly useful memory management references from RedGate Top 5 .NET Memory Management Misconceptions - Ricky LeekMemory Management Wallchart [ZIP]WPF and Silverlight gotchas [PDF]
Memory Management Misconceptions
Where’s your leak at? [Using WinDbg, SOS, and GCRoot to diagnose a .NET memory leak]
Delay's Blog : Where's your leak at? [Using WinDbg, SOS, and GCRoot to diagnose a .NET memory leak]
.NET Debugging and Stack Trace
When debugging enable the stack trace view to see where code has been triggered from. This is particularly useful for figuring out where events have been triggered from (delegation of event handlers from multiple places etc):
Mark Cooper 