Stickying some of these sites would be a very good idea.
I'll have a look around and see if I can find some more as well.
There's this site I found in the forums the other day, though I'm not sure what thread it was on. You probabely already know of it.
Telescope Simulator
I'm not too sure about the accuracy of this though. I viewed jupiter through my 60mm Telescope (an old one) with a 700mm focal length and a 4mm eyepiece, and I could see a bigger and brighter jupiter than the calculator claims.
I'll look around for some other sites anyway, and post them here.
