or ‘quicksilver on crack’ as David says.
www.azarask.in/blog/post/ubiquity-in-depth

1. FireBug – The only really necessary one.
2. Quick restart – All apps should have this.
3. Flashblock – Default ad-block.
4. Colorzilla – Get those hex colors.
5. Safari View – To email page or make a web-clip.