I'd ignore it, and buy bigger..
However if such a plan couldn't work (funds etc), I'd plant it thickly with small plants, and keep a betta and a few pygmy cories, or keep a shoal of something small (less than an inch), possibly Microrasbora kubotai, or a few male guppies.
However, as I said, unless something really inspiring hit me on what to do with it, I'd ignore it and buy bigger.