General .NET
MS and other Core .NET sites.
www.gotdotnet.com - The World-Wide-Web home for .NET
asp.net - The home of (you guessed it) ASP.NET on the web.
winforms.net - The home of Windows Forms on the web.
www.dotnetnuke.com - Community Starter Kits.
.NET Resources
Some of my favorite .NET sites. I visit most of these weekly if not daily.
Patterns and Practices - One of the absoulte best .NET resources available anywhere.
MSDN - Search it from Google, everyone else does.
The AspAlliance - Ooodles of Info, and home to a huge MS developer community.
IISFAQ - Everything you wanted to know about IIS (almost).
KBAlertz - Sign up for delivery of a daily dose of bugs/fixes/kb articles.
CodeProject - See what's cookin' in the kitchen.
LearnVisualStudio.net - A great resource for learning .NET.
SQL Server
Links to some Commonly used and referenced SQL Server Sites.
SQLServerVideos.com - Free SQL Server Training from a REALLY good looking guy.
SQLServerCentral - A great SQL Server and SQL Server Community resource.
SQLTeam - Links to all sorts of great SQL Server Articles and Resources.
SQLJunkies - A newer resource on the web that's shaping up quite nicely...
SS2005 - XML and Yukon. Great domain name!
SQLServerPerformance.com - Some of the best info on perf tuning out there.
Various References
A smattering of sites that house resources for all sorts of .NET related topics, like... web design, xml stuff, regex, etc...
RegularExpression Library - Just like it sounds.
DynamicDrive - A great DHTML resource.
ConnectionStrings.com - Heterogeneous connections in a jiffy.
MS Community Links
Sites that are geared toward interactions between developers for various forms of knowledge transfer.
www.microsoft.com - It would be pretty hard to have an MS community without MS.
DevAdvice - Forums for a variety of developer topics.
asp.net/forums/ - Forums for the war on ASP.NET
AngryCoder - Great insights on coding and life as a developer.
PC / Workstation
Useful sites that provide resources for tweaking, optimizing, and customizing your workstation.
SuggestAFix.com - A forum. Bring your quirks/problems.
Annoyances.org - Think you're going nuts? Nope, it's your OS.
BlackViper.com - Excellent performance and security tweaks.
Doug Knox - Excellent scripts and utilities for XP.
Aaron Margosis' Blog - A great resource for running with least privilege.