Shutterstock Photos is one of the sites I have been using a lot lately. They offer a huge selection of images, all professional quaility, though some a bit dated and a great selection. One option I have made really good use of is the number and diversity of vector art, especially for developing template background images.

Raster/Photo images: Yes
Vector images: Yes
Video: Yes (optional with subscription)
Audio: No
Pay Per Image: Yes average $10 each)
Subscription Download: Yes (25 images per day for 1, 3, 6, 12 month durations)

Test Search Results:
1. “Fast Car” = 17,206 results
2. “Medical Consultation” = 3,696 results

– Troy @ TLC