On July 29 2001 I had a day off from the Marktoberdorf summer school, during which I went to Munich to spot tracks. Here is what I brought with me back.
The Ostbahnhof map was done in a hurry, because I had to catch the last train back to Marktoberdorf. The S-trains coming from Giesing are supposed to reverse at Ostbahnhof and go to Hbf through the S-bahn tunnel. For that reason the Giesing line uses left-hand running (so I'm told - unfortunately I didn't have time to observe actual train movements there).
On coming home, I found that there is a partial overlap between my sketches and this map by Sven Zeegers. You may find it interesting to compare the maps. Sven's map continues south of Westkreuz to Garmisch-Partenkirchen.
A coarse sketch map of some locations north of Laim, by Gregory Beecroft, can be found at Rinbad.
Here is the line from Marktoberdorf to Munich (and vice versa). The part between Geltendorf and Munich is also on Sven Zeegers' map.