Ever since I started using .NET, I\'ve just been creating Helper classes or Partial classes to keep code located and contained in their own little containers, etc.
There's a web page dedicated to refactoring at http://www.refactoring.com/. It features many references to further resources on the topic of refactoring code as well as a mailing list to discuss refactoring-related issues.
Last but not least, there's a big (and still growing) catalog of refactorings available which extends well beyond what's written in the (very much recommended) Refactoring book by Martin Fowler.