Here’s a really cool feature in the VS.NET 2005 Debugger that I just noticed (duh!): Dynamic debug expression editing.

You notice that I’m in the debugger and highlighting a value. Notice that I can not only see value but also edit it right there in place! This certainly saves some time when you do need to muck with values as I often do in test situations.
The VS.NET debugger improvements are one of the highlights in VS.NET 2005 in my opinion. Debugger visualizers make life a lot easier, although some of the visualizers are pretty sad implementations <g> - cip: The dataset visualizer - yuk. Luckiliy you can write your own with minimal effort. The inline preview of objects too is pretty cool - there's a lot less need to actually have to create Watch points just to look at the data in your code.
While there’s a lot of stuff in 2005 that’s half baked and buggy the new debugger features really make life easier in day to day operations of the product.