Sort of following on the theme of Visual Studio customisations, here's one which I don't use: VIEmu is a piece of commercial software which provides full VI/VIM editing inside Visual Studio. There are also versions for Word & Outlook, and SQL Server 2005 Management Studio - each priced at $69.95. Ouch, however there are also a couple of package deals which mitigate the pricing somewhat. For the 3 people out there who happen to code in Visual Studio and love VI, then this is for you!
On a related note, I tried to adopt gVim (a Windows VI variant) as my text editor of choice recently. As much as people (including me) give VI a hard time, gVim happens to have a very cool feature in that it remembers a history of your last 10 command operations in a buffer. So if those were regular expressions, or search and replace operations which you happened to use on a regular basis then you could get some real productivity gains out of using it. Unfortunately I only lasted using it for a few minutes before reverting back to old Notepad (yep, not TextPad, not Notepad++, not anything other than original Notepad) so it was a failed experiment for me, but your mileage may vary.