If you are in need for a DC motor-generator for your project that has got real power,
try this one I just found on EBay:
http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=6066034347 (http://partners.webmasterplan.com/click.asp?ref=284148&site=1382&subid=&type=text&tnb=32&diurl=http%3A%2F%2Fadfarm.mediaplex.com%2Fad%2Fck%2F707-3922-3266-17%3Fmpro%3Dhttp%253A%252F%252Fcgi.ebay.de%252Fws%252FeBayISAPI.dll%253FViewItem%2526item%253D6066034347)
It looks like a nice little generator. But I looked it up and the shipper only ships to Germany, not the USA. :(
Here this Ebay USA offer might be a good offer
for US users.
General 6" Permanent Magnet Motor 24VDC 1200rpm
It can be used as an electrical generator, or as a water-wheel electric generator, or a wind-electric generator.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=6067231013 (http://partners.webmasterplan.com/click.asp?ref=284148&site=1382&subid=&type=text&tnb=32&diurl=http%3A%2F%2Fadfarm.mediaplex.com%2Fad%2Fck%2F707-3922-3266-17%3Fmpro%3Dhttp%253A%252F%252Fcgi.ebay.com%252Fws%252FeBayISAPI.dll%253FViewItem%2526item%253D6067231013)