Not perfect but it should help.
IMO, this should be a sticky. Also, most of those power ratings are PEAK. Actual operation values are lower (from my experience...approximately 25% lower).
General Rules (please add to the list or suggest modifications) culled from various power consumption websites:
3.5" HD: +15 Watts
2.5" HD: +5 Watts
Optical Drive: +15 Watts
USB Device: 5 Watt/each (Very HIGH estimate...personally, I would go with 1 Watt/each)
Various Graphics Card: ???
Various PCI Sound Cards:???