Well not really an informative post - but here is a quick list of what I deem to be essential to get coding:
Visual Studio (2010 or 2008).
MSTest - well if you have the above, you have this, but you should use it.
TypeMock - as you may have gathered I am a big type mock fan, although it is hardly used in a well architeched application, it still comes in handy... the range of isolate.verify methods you can leverage are useful, it also allows for private method testing without an accessor.
CodeSmith - typing code is very old school, generate it (or most of it!). Templates such as P-LINQO save mucho time when dealing with linq-to-sql. Penty of other cool templates around, but worth buying just for P-LINQO.
Resharper - Productivity. You really should have either this or Code Rush. Which you choose is personal preference.
GhostDoc - No one likes writing doco, so automate it.
TFS - Is of course essential if working on team projects. I would also recommend it when flying solo. Source control is a life saver!
Team Build - Full of C.I. goodness.
Firefox, Chrome and IE - you should probably test all web apps against at least these three.
Music - Who doesn't write better code with some good metal playing. - I am not really happy with any music players - so anyone have any suggestions?
What tools do you see as essential to .Net development? I know there are plenty of non .Net tools that are really good, but I am a .Net developer so that is what I am interested in. I don't want this turning into a MS vs Sun or MS vs linux thing!