As I've mentioned before, I love Resharper from those crazily clever folks at JetBrains. Today I installed an Early Access version of 3.0.2 into Visual Studio 2008 and all the goodness has returned. No need to write a Using statement again, error highlighting in C# without needing a build, the good old Ctrl-Shift-N keyboard shortcut among others. The 3.0.2 release has come a long way since the 2.5 release that I had been previously using, there are increased coding best practises and some nicer inline static anaylsis. The plug-in is also much more friendly in how it takes over any Visual Studio shortcuts and means that I don't have to re-train the old muscle memory when switching between keyboard shortcuts for actions in Eclipse and Visual Studio.
If you are spending all your day in Visual Studio then I urge you to take a look at Resharper. Personally, I find the increase in productivity well worth it, not to mention the increase in code quality that you get as a result.
I second that, Martin. As an early user of ReSharper (having used IntelliJ IDEA before that) right now I just can't develop without it anymore. Actually, it's quite funny when I go to another dev's computer which doesn't have ReSharper installed. I feel a little "impaired" - none of my shortcut keys work anymore! :-D
hear, hear!