This is the gallery side, so you should post your questions in the discussion side. I will, however, still answer your question. =) Halogens are basically incandescents, and put out bad light. It is yellow, and a lot of heat is produced.
A better choice would be a small compact fluorescent lamp, or even an LED. I saw a neat little thing at Wal-Mart that was a little fish bowl meant for a betta on a small black stand, and it had a small LED light above it, all built into the same stand. It looked very cool, and would make a great little terrarium, only slightly larger than a brandy snifter, and the same shape. I don't know if they have them in the States, but I would assume so.