Browsershots is a free online tool that makes screenshots of your web site in different browsers/versions on multiple platforms (Win, Mac, Linux).
Use it to test the look of your web sites :
Set your choices then come back later and see the results (here you can see my blog before/after the Opera fix):
On the live app you can click on a picture to get the full version.
Note: IE8 is already available, but no Silverlight yet.