Marilyn sent this note earlier
I am pleased to announce that Archivision Base, Module 1 and Module 2 collections - a total of 30,000 high quality architecture, landscape architecture and public art images - are now live in ARTstor for the convenience of the University of Calgary community! University of Calgary users may use these images as they would any ARTstor image. You will see this collection listed along with the others on the Welcome Page under the heading “Institutional Collections.”
Give this a whirl, especially if you haven't tried ArtStor before. It isnt' just for art remember, its also a great source of images for instruction and presentations.
Sadly, you can't then post your presentation to a public web page. Curse those copyright kill joys.