I used to rely on Google Chrome Inspect Element → Resources Tab → Stylesheets feature where I would double click anywhere in the css source and I could edit it with live rendering in the page. It doesn't seem to work anymore and that makes me sad. (I can do the same thing from the 'Sources' tab, but this requires more clicks)
I run Chrome v 21.0.1180.49 beta on OS X 10.6.8
PS. I found somebody else that has the same issue.