I recommend this book [ame=http://www.amazon.com/Nature-Walks-Southern-Indiana-McPherson/dp/0962846902]Amazon.com: Nature Walks in Southern Indiana (9780962846908): Alan McPherson: Books[/ame]
How far south? Charles Deem Wilderness area (part of Hoosier National Forest) just south of Lake Monroe & Bloomington is a decent spot to do some hiking.
There are a lot more hiking options in the HNF down near the river from what I understand, althought I've never been there.