There is an aviation museum halfway between Omaha and Lincoln. I tried to go once after work but it was too late. There is also a nice looking state park there as well.
http://www.sasmuseum.com/
The SAS museum is pretty cool.
Omaha also has the Stormchasers, a baseball team. As a history prof, I really like the UNL and Creighton library. Good steak as well in Omaha.