I've tabulated that, looked at a stack of schematics, and generally faffed around to come up with this.www.robgray.com/temp/Arduino-shield-pins-used.xlsIf you don't trust an XLS file here's a screen shotwww.robgray.com/temp/Arduino-shield-pins-used.png
But if it's worthwhile I can verify more over time, or maybe others can chip in or the owners of these boards can tell us exactly what pins they use.
When/if you get around to it, may I suggest a "verified" column that indicates that the info is almost certainly right.
Mowcius, do you mind if I have a go at setting up an online shield database or have you already started work on it?
Following on from that I'll add the ability to search by various criteria (such as pins used), compare shields, and submit new shields for inclusion. If anyone has ideas about other features they'd like to see please speak up.I'm hoping to make it publicly visible this weekend, even if it's just in a crude form.