If feel that the 40D's C1/C2/C3 and Green Star Menu features are one of the most overlooked features of the 40D. Once I got down to reading the manual (novel idea) I found these to be quite useful. C1/C2/C3 save ALL the camera settings. These along with user defined picture styles makes PS editing a lot quicker.
Here are mine:
C1
AV
RAW
6.5 fps
ISO 100
AWB
AI Servo
Evaluative Meter
All Focus Points
High Tone Priority OFF
C2
AV
RAW
6.5 fps
ISO 400
AWB
One Shot
Spot Meter
Center Focus Point
Highlight Tone Priority ON
C3
AV
RAW
Single Shot
ISO 1600
Spot Meter
Center Focus Point
High Tone Priority ON
GREEN STAR MENU settings
Quality
Erase images
ISO expansion
High ISO Speed Noise Reduct'n
Highlight Tone Priority
Sensor cleaning
My Menu Settings
I am still playing with these settings, but the ability to make one click changes to my favorite settings for situations is a great benefit to me.
btw...you can tell if Highlight Tone Priority is on by looking at the viewfinder or top LCD window:
ISO 4oo = ON (note the little "o's")
ISO 400 = OFF (off allows ISO 100 and 3200 to become available..
)

