Code:
L01
L05
M09 (used it for some time before finding EPOM plugin, which offers a more comprehensive similar feature)
M13 (I never tried it, but when I knew this was possible it was good to know)
M24 (Katja made me remember that, from time to time, I like to take a look at the timestamp graph)
U01
U09 (!! found it today, might be useful)
C59