Two important questions - how much light will this thing get, and how long do you want it to be able to be left more or less alone before requiring radical work (major cutting-back or removal of some plants or total replanting)? (Small auxiliary question #3: what temperature will this be at - warm room temperature, or getting cool at night?)
If you could give some hint about those things we could probably make better recommendations. But, as a "generic" answer, some usually-all-purpose easy-to-find small terrarium plants would include small ferns, selaginella, creeping fig, creeping charlie (if you cut it back frequently!), baby's tears (ditto, and best in fairly bright light), and my all time favorite small terrarium plant Fittonia (I prefer the white-veined one, but it comes in pink too). For a larger plant in a small terrarium, consider prayer plant, small rex begonias, cryptanthus, spiderplant, smaller philodendrons, or a young specimen of the Chamaedorea (sp?) palm. Pepperomias make good terrarium plants too IF you have really really well-draining medium, but will rot if they get soggy feet.
There are a number of other plants often used in terrariums (swedish ivy, dracaena, croton, larger ferns, larger palms, etc) BUT they will fairly quickly outgrow a 10g tank.
(e.t.a. - I should also mention one of my other all-time favorite sort-of-terrarium plants, the jewel orchid, whose latin name used to be Haemaria but I kind of think it may have changed, anyhow it has gorgeous burgundy-ish pinstriped velvety-looking leaves. Flowers are ok but it is basically a foliage plant. It does quite well in very bright indirect light in an open-topped fishtank, so you have somewhat elevated humidity but not stagnant air. If you are considering an open-topped terrarium, this makes an awfully nice centerpiece

)
Good luck, have fun,
Pat