Here are some online resources for getting free maps:
Tennessee River: http://www.orn.usace.army.mil/opn/TNRiver/
Mississippi State lakes: http://www.mdwfp.com/level2/Fisheries/pdf/maps/
Ohio Lake & River Maps: http://www.ohiodnr.com/Wildlife/Fishing ... /lmaps.htm
And from Fran Myers' posting in tools and controls:
Wisconsin: http://dnr.wi.gov/org/water/fhp/lakes/l ... maps_p.htm
Minnesota: www.dnr.state.mn.us/lakefind/index.html
Michigan: http://www.michigan.gov/dnr/0,1607,7-15 ... --,00.html
For paid for maps a great site is
http://www.sportsmansconnection.com/