St. Louis is a great city for baseball, not just because of the St. Louis Cardinals. The metro area hosts two teams of the independent Frontier League, the Gateway Grizzlies and the River City Rascals. In 2005 and 2006 I saw (way too) many Grizzlies games, both home and away.
If you ever make it to St. Louis, check out the schedule of the Grizzlies and Rascals and try to attend a game or two. The Grizzlies ball park is fameous for its weird (yet good) foods and was recently elevated to one of minor leagues's top 10 arenas.
Check out some of the photos I took in 2006.
And here are the links to some Frontier League teams:
River City Rascals, O'Fallon, MO
Rockford Riverhawks, Rockford, IL
Evansville Otters, Evansville, IN