Teamviewer might work, I know it does when trying to connect to your PC normally.
There's a free teamviewer app on the app store, download that and download teamviewer on your VPS and try it out.
There's also one called LogMeIn which does much the same thing as Teamviewer.
I love how everyone answers this without asking a critical question... Is it a Windows VPS or a Linux box?
The app store has an app for putty in the app store, and I use TeamViewer PRO for my Windows VPS, unfortunately, it won't work if the PC is off... but then again, what kind of VPS goes off for no reason?

