Suggestion #1
Safety Suggestion

For any file extension that can be potentially dangerous it would be nice if users could vote saying weather it may be a virus, Spyware or what not. And showing an amount and percentage of people claiming it to be a virus. I understand this could pose a problem, as it would be a lot of data to keep track of considering there are millions of files, so this suggestion may not be practical. Maybe a better way around this would be to have an automatic online virus scanner after the file is downloaded (maybe leave it as an option weather to scan them or not.)

Suggestion #2
Organization suggestion

Allow specific file extensions to go in specific sub-folders (i.e. avi,mov,mpeg goes to Videos; mp3,wav goes to Music; exe,zip goes to Downloads; you catch my drift.) Obviously the user would be able to set which files go into which sub-folders and what the folder names are. Lastly maybe add users logins say I go on and all my downloads go into my folder with all my subfolder preferences. Then if my roommate wants to download her files goes into her own folder so her crappy downloads do not get mixed in the same folder as my cool downloads.