Visual Studio has certainly gone from strength to strength since humble Visual Studio 6 (and previous renditions). There seems to be a lot more coming in Visual Studio 2010 (based on blogs, the PDC and the more recent CTP virtual machines).
The recent Service Pack 1 seemed to introduce some really intriguing new functionality and enhancements.
As it stands today, i.e. in Visual Studio 2008 (SP 1), what do you think is the most outstanding, couldn't-live-without-it feature in Visual Studio (including the Team Suite Editions)? Is it something you use daily?
Alternatively, what features in Visual Studio 2008 could really use an upgrade/makeover/bugfix?