Quick (old) Tip
One of my team members showed me this one a while back, but I had to use it again today.
A using statement can have a variable receive the "value" of a namespace. For example, I can do this:
using App = MyCompany.MyApplication.Framework;
This is particularly useful in resolving ambiguous references (e.g., a System.Environment class and a MyCompany.MyApplication.Framework.Environment class). Then, instead of fully qualifying it I can shortcut it (e.g., App.Environment).