If you're looking for specific graphics for your BBP presentation, but you can't find them when you search iStockphoto, try posting your requestion at the iStockphoto discussion forum.

Visit this link (iStockphoto log-in required) to visit the Image, Illustration and Video request, and post what you're looking for.  Give as much detail as possible, in terms of the illustration details, layout, colors and size, and see if other iStockphoto members can either create a new graphic, or point you to a place to get it.