If you're not already using Dropbox, we have to ask: What are you waiting for? This popular service lets you easily sync files between computers, share with them others, and create backups. Best of all, it integrates so seamlessly with Windows -- and other platforms -- that you're barely even aware that you're using it. This program is a must-have for anyone who needs to make their files readily available to multiple users or computers.
Once you have a free OneDrive account, you can also install the free OneDrive desktop app and automatically sync your files across your computers. You've got access to everything on your OneDrive wherever you are: Your photos, documents, and other important files are available on your phone, tablet, PC, or Mac. In short, your files and info aren't stuck on any single PC or device. Get free Word, Excel, PowerPoint, and OneNote in your browser with OneDrive and free Office Web Apps. Share only the documents that you choose, with whomever you choose, and set the rest to remain private. Prefer to use the full-featured, desktop version of Office instead? Don’t worry, SkyDrive works great with that too. Website: onedrive.live.com/about/en-us/download/