CoolCommands is perhaps one of my favorite add-ins for Visual Studio 2005 — perhaps even more so than TestDriven.NET. Check out Gaston’s post for some of the details of its goodness. Suffice it to say that I use features from it on a nearly hourly basis as I’m coding.
The URL for the tool is wrong on the post page, though. You can find CoolCommands’ installer here now.