What kind of lenses should I get for a Canon T1i?

If you really want to get her the best of the best, get her a Canon 5D mark II since it has a full frame sensor whereas the Rebel series doesn't. Regardless, it's worth it to invest in good gl (lenses) now even if she will upgrade her camera body later. Get her a 50mm prime lens, a 16-35mm L wide-angle lens, and 70-200mm L telephoto lens. If she does a lot of outdoor photography it's always worth it to get circular polarizer filters for each of the lenses. For lighting, she could start with the Canon 580ex2 strobe. And if she uses off-camera lighting at all, pick her up a lightstand with an umbrella and a couple of Pocket Wizards.