Great painters talk all the time about where to find a good brush, they say. And the mediocre ones? About styles and trends!
Well, we Marcom folks talk all the time about images. My personal all-time favorite is istockphoto. Mostly at 1 dollar a pic, (Except illustrations), iStock helped us create the "winning ambiance" for 2 of our successful Fortune 10 presentations last year.
Another good resource may be the open-sourced images in Flickr.
Presentation Zen has a good list. Find it here.
Jay, from Bangalore