Recently I have been making a move towards TDD (Test driven development) leveraging NHibernate and NUnit to aid in the transition; seems to be working good so far, can't say I am 100% sold yet, but I may be on my way - will post later if/when it occurs
some good reading
Domain-Driven Design: Tackling Complexity in the Heart of Software
Applying Domain-Driven Design and Patterns: With Examples in C# and .NET
some useful links
will post more later...