I'm not really one for joining causes online (Facebook has rid me of any desire for that), but as far as geeky technical causes go, Bring Down IE6 by the folks at .NET Magazine is a good one. Internet Explorer 6 is the bane of pretty much every web designer or developer's existence. Things that work beautifully in all of the standards-compliant browsers (and even for the most part in modern versions of IE) require time-consuming and painful work-arounds just to get them sort of working.
The frustrating thing is that if Microsoft wanted to do something about the situation to ease the pain of the countless numbers of people building websites, they have it in their power to do so. The problem for web developers is that IE6 is still used by a frighteningly large percentage of people online. How can this be? Well, many unfortunate corporate workers are stuck using Windows 2000, and do not have permission to install or even use a portable version of a standards-compliant alternative browser like Firefox. These people are using IE6 because it is the only option available to them.
As much as Microsoft would like to force everyone to upgrade to XP / Vista / Windows 7, the truth is that for many companies, the Windows 2000 licenses that they already own work just fine for their needs.
What Microsoft should do is acknowledge that Windows 2000 is still being actively used, and make later versions of Internet Explorer available as an update for Windows 2000. Yes, I realize that Windows 2000 is no longer an officially supported platform by Microsoft, but that just points to the disconnect between what Microsoft wishes people would do, and what they are actually doing.
Also, if you're in IT at a company that is still clinging to Windows 2000, for the love of all that is good, please add a modern browser to your standard install image. They're free, and they're a hell of a lot more secure than IE6 is. Pick one; Firefox, Opera, Safari, or even Google's currently-in-beta Chrome browser. Any of these is a better choice than IE6.
And if you're a web developer, consider using a simple script to provide a gentle reminder to IE6 users that they need to upgrade.
Let's all let IE6 die the death it so richly deserves.