If you like the idea of rescues and want to go aquatic, there are tons of turtles out there needing forever homes! Your tank is a nice size and can be good for several species so long as you research before hand to make sure it's not going to get too big. So many people buy baby turtles, and then dump them when they need a bigger tank. Many have MBD or deformities from improper lighting and diet.
I had a rescue turtle for a few months this spring until a horrific unpredictable accident involving a suction cup. (I was a mess for a week afterwards. I loved that little dude!) I never thought I'd be a turtle person, but I'm always on the lookout for a watertight big tank at a good price because I want to adopt a few. Our local reptile rescue has over a hundred Red Eared Sliders right now, and can never find anyone who wants to adopt them. They are very interactive and extremely funny. More work than a fish tank, but I personally think more rewarding.