Sundew (Drosera) are great terrarium carnivorous plants, especially for beginners. Asian pitcher plants (Nepenthes) are slightly more advanced and can be more difficult to grow well depending on how well you can control your temps, plus many nepenthes outgrow terrariums quickly. Sun pitchers (Heliamphora) are a step above nepenthes in terms of difficulty.
Mexican butterworts (pinguicula) also like higher humidity, but you have to drop that humidity to 50/60% during winter or they may rot. This may be a problem in a terrarium, as controlling exact humidity levels can be a daunting task.
I'd think your best bet is tropical and subtropical sundew:
Drosera capensis, spatulata, natalensis/venusta, adelae (though adelae can be finicky), aliciae, prolifera, paradoxa, sessifolia (annual), or burmannii (annual) would be good starts.
Capensis is the most popular/common of these and the leaves will actually wrap around their prey in a couple hours. The annuals are slightly more difficult because they start out so small they can be hard to feed; use crushed freeze-dried-bloodworm which you can get at any pet store. Bigger drosera do very well with betta fish pellets as food. Both of these smell a lot better than half-decayed insects.
Here's a great resource for sundew:
http://www.growsundews.com/ (here are
specifics about feeding)
A fun drosera project for you to try later on, if you do decide to get any sundew for your terrarium:
http://www.thecps.org.uk/content/view/87/40/
Good luck