If you're a fan of improv, check out TV sitcom, The League.
The whole show is semi-improvised. As far as I'm aware, they have a basic plot but no actual script as such, they just riff on the ideas while they're shooting.
Brilliant show. Gutted it's now finished. Still, we got a decent number of seasons out of it and it brought Jason Mantzoukas, Nick Kroll and Paul Scheer into the public eye amongst others.