People tend to check in during these times:
Avoid the canteen... especially on Fridays
Cafeteria next to Mosaic Hall is open till 5pm and serves nixe snacks.
Visit "Eichensaal" (oak hall), the room for decision in the eastern wing
You can get good fresh Pizza at the canteen in the "Verwaltungsgebäude" :-)
Make sure you have your badge! Signing in is a pain without it :)
hehe...i agree to the tipp about the canteen...avoid it!