If you are a downloader then this is a pretty handy page. Check the Validty and Availability of the links from these sites in one click.
Sendspace.com
Megaupload.com
Rapidshare.com
Rapidshare.de
Badongo.com
Depositfiles.com
Easy-share.com
Filefactory.com
Mediafire.com
Megashares.com
Pirateshare.net
Turboupload.com
Uploading.com
You-love.net
Zshare.net
http://www.mtworld.info/filec/