Some variety of crassula (jade plant)?

Gary

Definitely a Crassula ovata, known as Jade. There are several different varieties of C. ovata: some variegated, some with larger or smaller or differently-shaped leaves. And there are some other Crassulas which closely resemble C. ovata, a few of which are also called 'Jade'.

In addition, there is Portulacaria afra, which is sometimes confused with C. ovata, and is sometimes called 'Baby Jade' (though it's not). It has smaller and rounder leaves, smoother and often red stems, and also has a variegated version.

Your Jade looks quite happy. The leaves are fat and healthy. You must be giving it the correct amount of water. And the stems haven't stretched, so it's getting enough sun.

Crassulas' growth spurt is in the spring. You'll have to wait till then for growth -- but if you're lucky, yours may flower during the winter.

If you don't like the shape of yours, you can take cuttings to form new plants. (Just be sure to let the cut branches callus before planting or watering them, or they'll rot.) But trimming a Jade doesn't stimulate out-of-season growth. On the other hand, trimmed Jades do branch more.

Here are some threads on GW's Cacti & Succulents forum about how to "whack" or shape a large Jade:
http://search.gardenweb.com/search/nph-ind.cgi?term=whack+jade&forum=cacti&forum_name=Cacti+%26+Succulents