I'm becoming a big fan of Dropbox. At first glance, it's an online backup service. But it also synchronizes files between computers, keeps a revision history, shares files/folders between Dropbox users, and shares files/photos online. Plus it's cross-platform (Windows, Mac and Linux). It's like the Google GDrive that has never materialized.
It's practically replaced my USB flash drives. No more digging in my laptop bag, worrying about safely removing the drive, forgetting to take the flash drive with me, or finding a flash drive in the clothes dryer. No more worrying about forgetting to back up all those LOLCats photoshops.
Since I work on several computers during the week, this has saved me a lot of time and trouble. No more having to remember to email myself that document to review. No more wondering if I have the latest copy of the readme file I'm editing. No more wrestling with Windows file sharing at home.
Their 50 gigabyte plan is $9/month, or the 2 gigabyte plan is free. If you use my referral link, we both get an extra 256 megabytes of free storage.