A friend of mine showed me what looks like a nice (free) secure remote access solution for visually managing a remote PC:
It’s based on TightVNC and therefor has the advantage of using encryption on the control session, helping reduce the risk of prying eyes. It also has a pretty cool way of letting the user choose to delegate or not delegate control by reading you a generated key. In particular it looks pretty handy to maybe manage those pesky (note, I’m smiling when I say that) friends and family when they get into trouble.
Definitely worth looking into. From what I undestand it works on both Unix and Windows.