There are so many things to see in Taos! The biggest and most important one would be Taos Pueblo, which is the oldest continously inhabitated town in the United States. Be careful to research before you visit, as the pueblo is only open at certain times of year and there are various restrictions on conduct and behavior. Remember, also, that this is a functioning village with deep historical significance, and to be respectful of the people who live here.
Visit http://taospueblo.com/ for more info!
Next, drive out to the Taos bridge! It is a breathtaking bridge and certainly worth the 30 minute drive from town.
One of Taos's most unique attractions is the Earthship community! These strcutures are homes built into man-made hills, and are often 100% energy independent. The community is open to the public to visit, but they are homes, so be prepared to respect the resident's privacy.
Finally, make sure to wander around downtown Taos! There are lots of great shops galleries which are best accesed by foot. Taos Plaza has events often during the summer, and if you're lucky, you'll chance upon one!
Taos Pueblo
Gorge Bridge
Taos Earthship Community