Stones River Greenway
If you live in or near Hermitage, you should check out the Stones River Greenway. It's a great walking path on a nice scenic river. The greenway is not complete yet, but if you start from the Percy Priest Dam trailhead, you can go all the way to the Kohl's on Lebanon Pike before the trail ends.
From a recent announcement, it looks like the full greenway won't be finished until sometime in 2008 since TDOT is going to build a new bridge on Lebanon Pike and the old green truss bridge will be used exclusively for the greenway after that.