You can reach Oberammergau by train from Munich central station (München Hauptbahnhof), you have to take the train headed to Innsbruck (a regional train that departs on daily basis) and switch trains in the Murnau train station (the train to Oberammergau is the only other train in the station), the trip from Murnau to Oberammergau shouldn't be a problem, since Oberammergau is the last station to be reached.
You may also reach Oberammergau by car, you would have to go to south Munich in order to the take the Autobahn A-95 south to the Ettal exit. From there on the B-23 to Oberammergau.
Getting around Oberammergau shouldn't be a problem since it's a relativly small town. You can get around (as most locals do) walking, but you can also take the bus (there are a couple of bus stops in town), you could also get around by car, and like most of youth by bicycle.
Every 10 years, the Passion Play  is performed. The next performance will be in 2010, but you can also visit the Passion Play theater where you can take a tour, in which many different aspects of the play are explaind. The tour is usually available from May to October, from Tuesday to Sunday at these times 10:00, 10:30, 11:30, 12:00, 12:30, 14:00, 15:00, 15:30, 16:00, 16:30, 17:00. The tour is also available on Mondays during the Holidays.
Most of the buildings in Oberammergau have beautifully detailed murals on them, mostly of biblically significant tableaux.
There is one beautiful Catholic Church in Oberammergau, it has a baroque style, although Oberammergau is known for being a Catholic Town there's also an Evangelic Church.
Near Oberammergau (ca. 5-7 kms) you can find Ettal Abbey. A beautiful Abbey, School, Boarding School, and belive it or not a brewery.
Also you are going to find the Linderhof Castle (Schloss Linderhof) one of King Ludwig II's dream castles. Known by being one of the few finished castles the King actually used (at least as a Holidays residence). There are tours between April and 15 October from 9 am to 6 pm and between 16 October to March from 10 am to 4 pm, the castle is open daily except on 1 January, Shrove Tuesday, 24, 25 and 31 December. The Admission fee for a Palace and park buildings tour is of 7 euros, and in winter only the palace can be visited with the admission fee being 6 euros.
Visit the Kreuzigungsgruppe (Cruxifixion Group) a monument in the Oberammergau Mountains. The monument was a present from King Ludwig II, after witnessing the town's Passion Play in 1870.
For a small town Oberammergau offers a great variaty of places to eat. If you don't wish to spent too much money in food you can try eating at one of the imbiss (bars in which food is also served). You can also eat at one of the many hotel and guest houses (where among international food, local food is also served). Desserts are to be found not only in the restaurants but also in some cafés.