Remotely monitor/restrict Internet use

Is there any app/software available that would let me track internet useage (or even restrict it) on another computer. Grades are slipping due to gaming and net surfing, unfortunately they don't live at home anymore.

Don't know about Canada's laws but in the US if folks don't have direct 'control' of dependents they could violate several laws, both state and federal, especially where separation or divorce or custody is involved. There are programs such as Logmein and Remote Access but they can be circumvented by the user of the computer in question, one of the simplest would be changing ISPs and not letting you know. If those involved are minors it would mostly be up to the adult in charge.