Dean Edwards’ IE7 script

This set of script files, found here, are a cross-browser programmer’s best friend. Upload them to your server, link them into your page with a simple script tag, and voila, you add web standards to your IE browsers. For me, the alpha transparency and min-width stuff is worth the price (it’s free!), but it contains so much more. There is also a google group you can join that Dean himself contributes to.