Other OSes it works with: BlackBerry, iOS, Android, Windows Phone 7

Price: Free

Dropbox lets you store files online and sync them with multiple personal computers and mobile devices -- so as you add, delete or modify files on one device, those changes will be reflected on your other Dropbox devices. A login account with 2GB of is free to anyone who wants to sign up. Multiple people can share a single account to create workgroup file sharing; you can control access to specific people or specific folders. Two paid options let you store 50GB ($9.99/month) or 100GB ($19.99/month). After trying several other -based file-sharing tools, I settled on this one about a year ago and have never looked back. --Scot Finnie