The 2012 Robin Hood Festival from 13-19 August.
The tourism site for Nottinghamshire. That one should keep you busy, there's loads on it.
Peak District website. Again, packed with stuff.
Leicestershire and Lincolnshire are also worth looking up.
I think I must have been just about everywhere in the area! It's not possible to get bored! There's even a wurst shop in Bakewell...