So does Firefox (Ctrl + Scroll). I don't know if SeaMonkey's works for flash and other such, but Firefox's does.
Dude did you bother to read the pros for FF?
~DID AN ACID 3 TEST ON ALL OF THEM~
SeaMonkey: 53%
FireFox 3.0.1: 71%
Opera: 83%
Internet Explorer 7: 5% (According to UndeadDragon)
Also: IE6 does not support transparency in Portable Network Graphics. Fail.