http://lunacommons.org/

"New centralised dbase of all the Luna InsightBrowser sites -- incredible array of material available [eg. 13000+ photographs; 13000+ prints; 12000+ maps etc etc] from a wide variety of repostories (mostly university-type institutions). I have not played around much but this makes accessing the material really really easy compared to normal." (peacay on delicious, thanks for the alert)