www.browsershots.org
ipinfo.info/netrenderer/
www.browsrcamp.com (Safari 3.1.2 only)
www.crossbrowsertesting.com (via vnc or java applet. often not working. when it works its great.)
www.litmusapp.com
www.browserpool.de (did not get it to work)
browserlab.adobe.com (did not try it, because it asks me to install flas 10 and i heard that you need an adobe account)
