1. URL upload would be nice
2. Copy most popular files to another server - also good idea
3. Badwords/filename filter - another
4. anyway to display links like: http://www.mysite.com/5dsa2d1asd ?
5. optional resume upload maybe?
6. turn on/off download managers support (resume, threads etc.)
7. max connections from the same IP
8. limit download and upload speed
9. direct download option from premium users
10. would like to see recommended php.ini httpd.conf and myslq settings, also does it use /tmp directory while uploading? if so, how big it should be to handle about 1gb uploads?
11. creating folders to put files?
12. if user A uploads file and that file will be downloaded by PREMIUM user B, user A will get 1 point and he can later exchange it to premium package or money maybe
13. desktop uploader? with resume upload capeabilities and upload Queuing maybe?
14. limit disk space for users?
15. expiration info in user control panel
16. embedding WebDAV ( http://en.wikipedia.org/wiki/WebDAV )
17. multilanguage support and language selection for users
Going little extreme now

18. Youtube video downloader-converter-uploader
user puts youtube video link, server downloads it, converts to avi and gives back link (pretty much resource intensive I guess)
19. Tagging uploads and tag cloud
20. text download link or button download link (optional)
21. wap version of the site, where users could type in file ID (from cell phone) and get their file
22. small flash based mp3player for uploaded mp3 s
23. small video player - for uploaded vids
24. uploaded images can be automatically viewed
