SkyDrive Explorer adds 25gb of free cloud storage to Windows Explorer
Once you install SkyDrive Explorer, you'll see a new icon in My Computer (under "Other"). Double click it to open your drive, and a Live login window will appear. Sign in and you've got full-on access to SkyDrive right from Windows Explorer. Add files and folders, move things around, delete old junk - all as if they were stored on your local hard drive.
I'd like to see the app allow access to SkyDrive from open and save dialogs, but it's a great addition to Windows even without that functionality.
SkyDrive Explorer runs on both 32 and 64-bit Windows.