I collected a number of IE hacks tutorials over the years. Here is the list which you can find great tips for your websites.
IE6 hacks and tips
1. 10 Fixes That Solve IE6 Problems
2. Obituary For IE6
3. Feed IE 6 with a basic stylesheet
4. IE CSS Bugs That’ll Get You Every Time
5. Defensive coding and CSS: Preventing the most common bugs
6. Closing the gap between list items in IE
7. 5 Easy Ways to Tackle IE6’s Transparency Issues
8. Don't kick your visitors's IE 6 and below out of your css layout
9. Let Internet Explorer 6 Behave Like Internet Explorer 7
IE6 Blocker scripts.
One way is to educate your audience by suggesting to a better browsers.
1. IE 6 Blocker Script
2. A simple IE6 upgrade script
Demo for above script are here. You have to use IE6 to see the effects though.
IE 6 Blocker Script Demo
A simple IE6 upgrade script Demo
Tools
1. Internet Explorer Application Compatibility VPC Image
2. IE6 standalone
3. IE tester
4. netrenderer
If you know more, please add them to the comment.