Finally installed Firefox 2 on my machine (actually, installed both, Firefox 1 and 2) and immediately searched on how to remove that fugly gradient background of the tab bar. Too much depth there Mr. Ozilla!
Displaying the 'Firefox' category
Remove gradient background from Firefox2’s tab bar
DNS error page instead of popup in Firefox
Fix that pesky focus stealing popup!
Remove horizontal separators in Firefox
It’s a very small detail, but in my Firefox doesn’t have fugly horizontal lines!