There is SO much to do in Munich!!

If nothing else, head to the city center. There are many things to see, do and shop for. Like most of the cities in Germany the city center is where most of the life is at and the majority of the resturants, so there will always be something to do. A really nice cathedral is located in the center and it is called Munich Frauenkirche, very beautiful. The Hard Rock, Munich, is also located within walking distance to the center. I don't know about you but I always like buying the guitar pins when ever the opportunity is available.
Another is the Nymphenburg Palace and Gardens but it is further away from the center of the city but I don't think that it will be too hard for you to find some helpful information on how to take the streetcars to it. Luckily when I was there I was there with a local that had everything planned out, that is always a good thing.
Another thing and my favorite out of everything that I did was visiting Dachau. Dachau is a town not far away from Munich (about 20 minutes by train) that is home to the first concentration camp in Germany. It was the model that set the building plans and standards for the rest of the camps and the SS was also trained there. Over 12 years, the camp housed over 206,000 prisoners and 36,000 people died. Hitler called Munich "The Capitol of the (Nazi)Movement" and his rise to power was centered in and around Munich. But you should really consider this life changing tour. They offer a few English speaking tours through out the day but I can't remember the exact times so you may want to Google Dachau.
The Olympic Park is also in Munich. It is most famous for it terrorist attacks on the Israeli's in the 70's.
And last but not least there is the Neuschwanstein Castle that isn't too far from Munich. A beautiful place (although my trip got canceled) :( and is what the Walt Disney castle got it's imagination from.