If you are a baseball fan, there are a bunch of minor league teams in IA.

Des Moines has the Iowa Cubs (AAA)Chicago Cubs

Cedar Rapids has the Kernels (A) L.A. Angels

Burlington has the Bees (A) K.C. Royals

Davenport has the Quad Cities Swings (A) St. Louis Cadinals

Clinton has the LumberJacks (A) Texas Rangers

There are also a few teams in Illinois.

Look here for games and times
Midwest League

Cedar Rapids has a newer stadium that I haven't been to yet, the Quad Cities Stadium is pretty cool. South Bend and Fort Wayne (IL) have nice stadiums also.

I used to work for the Waterloo Diamonds (now the Lansing Lugnuts) and traveled with the team on occasion. Minor league baseball is a great way to spend and evening!