Today Google Drive and Windows SkyDrive came out with clients for Windows and Mac. There's also SkyDrive apps for Windows Phone, iPhone, or iPad and OneNote apps that sync to SkyDrive for Windows Phone, Android,iPhone, or iPad.
I'm a paying DropBox customer myself with over 60 gigs in there. I also use BitBucket and GitHub for source code.
I also like tidy and pretty icons, for folders, programs and external drives. I made custom icons for the Visual Studio Command prompt as well as Visual Studio in PowerShell.
I put all these new cloud folders as well as my GitHub and BitBucket folders (these aren't custom apps, just folders where I keep my source repositories) in my favorites in Windows Explorer.
I made custom .ICO icons for GitHub and BitBucket from high-res PNGs. Just right click on a Folder, click Properties, then Shortcut Change Icon to select your custom icon.
Read more: Scott Hanselman