Thanks a lot for the discussion so far folks!
1. I agree about needing debugging after IE 8, especially for older IE scripting engines…but it is heavy on the VM! Not sure what to suggest really. The IE 6-8 emulator someone mentioned above sounds very interesting and worth a try.
2. Firebug - I know they are doing a lot of improvement work on it right now…possibly because of all the work we are doing on Opera Dragonfly…lol ;-)
3. Screw-unit - thanks for the tip
4. Webkit debugger - it’s good to see this being improved upon as well.