TortoiseSVN - The coolest interface to (Sub)version control
Dropbox - Online Sync and File Sharing
SnailSVN - Similar to Tortoise SVN for Windows but integrated into Finder
ownCloud - ownCloud is an open source project enabling businesses to host their own cloud storage while maintaining regulatory and compliance needs.
Xversion - Super easy enterprise class version control.
Google Drive - Access and sync your files anywhere