Add a query string to your style sheet link for cache busting
I wrote this post a while back. The content can still be relevant but the information I've linked to may not be available.
I was looking at the UX London website recently and I noticed that their CSS files are referenced with a query string like this:
<link rel="stylesheet" type="text/css" href="/css/screen.css?20090108" media="screen">
The query string  looks like the date. This seems to be a rather neat method of preventing style sheet caching when your CSS changes. It's not something that I have come across before but it's a clever idea implemented by Jeremy Keith and Natalie Downe at Clearleft.
Update: Confirmed on adactio's Twitter stream