My search resulted in 721 different ".app"s and, of course, that doesn't include Classic applications or Carbon apps that don't need the .app extension. I guess it would be more if I reinstalled the old software and games I just have on CDs.
To put that into perspective, the above list has 305 entries.
Edit: Oh crap. I hope this doesn't turn into an "I have X more apps than you do!" discussion.