The Apple X Server: X11 for Mac OS X. Awesome!
Funny AlBook commercial: Big and Small.
Safari made me realize that I really don’t like tabbed browsing; I was just using it because everyone else liked it so much. (Update: Or maybe it was because Chimera is so slow otherwise. Either way, another point to mpt.)
On the other hand, I do like spell checking in text-edit forms like this one! :-)