I purposefully leave my downloads on the desktop, otherwise I end up with gigabytes of .tar.gz and .img.sit files lying around for months. Besides, OmniWeb has a 'Download to Desktop' item in its context menus, so this way I don't have to look in 2 places for things. Although I wonder if the menu changes the download location if I change my prefs... hmmm....
I find that when I start putting things on the desktop I end up with files multiplying. All of a sudden there is a HUGE clutter of miscellaneous files
g4 400 AGP - 512 RAM
10GB internal (dumping ground) + 60GB (30 GB OSX partition/30 GB OSX Server partition) - 3GB external SCSI (OS9/and I think the Public Beta is still on there somewhere) - DVD-RAM - ZIP