Freemium software with a 3 gigs option with a max of 150 megs for individual files. Requires registration with service -- no idea what sort of security/privacy this system uses.
Steps:
Download installer and extract using 7zip to a folder. Launch CloudMe.exe
Status: Not portable, writes to C:\Users\USERNAME\AppData\Local\CloudMe\Sync
One nice thing about this program vs. so many other sync tools I seem to use is that it's only using around 22 megs.