I regularly tutor people in programming and act as a helpdesk, am considered a good tutor/helpdesk, and I would never offer my tutoring/helpdesk services at that puny rate. I absolutely love the idea, but you NEED to let the tutors set their own rate. Anyone want to build such a site, possibly working with me? I own "software-shaman.com" and have been meaning to set it up for something like this, but haven't felt any…
A $/hour scale is going to be the easiest way for me to ascertain the skill/knowledge/experience of the tutor.
Initially I'd be happy with someone outside the US - hell, I might even continue with someone from outside the English speaking world - but having the variable would be nice.