You could face a potential lawsuit if you monetize it...Harry Potter is a TM name (though you'll probably get away because its a fansite...I'd suggest you ask the people in the legal section about this)
so again, whats the traffic like? Any revenue?
The name by itself is worth nothing, but you've got content and potentially traffic...
I get quite little revenue. Maybe $ 10 -$20 / month because I'm just trying to get into adsense alternatives. Its been only a little more than a month that I've displayed non-Adsense ads.
Hmm...then this would be worth in the mid xxx range (taking $10/month as the revenue for 2 years. This would of course, increase with time as the website gets more popular, but right now, mid xxx with the current traffic/revenue)