I know there's sites where you can play songs in a certain key, and it'll tell you what the songs key is in, and you imrpovise a solo to it. Its like a backing track kinda thing. someone have a site i can go to?
"My jedi powers are far more superior than yours"
i just get on guitar pro and set some chords (I IV V blues progression for example) and put it on repeat. maybe you can do that in power tab?

don't know of any sites though. :/