How much current do the LEGO motors draw?
YES!  Philippe Hurbain (Philo) has put together a great and very detailed write-up on those and many other LEGO 9V electric motors.

You can find it here:  LEGO 9V Technic Motors compared characteristics

Your current draw for that specific motor @ 9V is:

No load:              65mA  
Loaded (3.6 N.cm):    310mA  
Loaded (6.0 N.cm):    480mA  
Stalled (11 N.cm):    850mA




I was about to ask this very question when a friend pointed me to this write-up.
Hopefully someone else will find it as useful as I did.