If anyone is thinking about getting a reptile pet during med school, I'd like to recommend getting a leopard gecko and NOT an iguana or chameleon.
Leopard geckos are easy and low-maintanence. You make sure they have water and feed them one or two times a week (more when they are babies) and dust their food with vitamin powder, and they are good to go. You can easily leave for a weekend, and they will be fine. They don't even need UV or sunlight (well, a little bit of sunshine is good for everything, though). The only major concern you have with them is making sure that they shed completely and properly. If you spend a lot of time with them when they are young, they will be affectionate with you, and they live for ~10 years.
Iguanas and chameleons, on the other hand, require UV light, which can get expensive, and when they grow bigger, you may need a very large cage. Their diets are also more complicated. I love iguanas and chameleons, but I've seen many malnourished, sick, neglected iguanas returned to pet stores simply because their owners didn't know any better. Please do a LOT of research before you pick one up.