Here's a few more:
http://www.shutterstock.com/g/kkeifer
http://www.bigstockphoto.com/search/photographer/KennethKeifer/
http://www.cutcaster.com/studio/pub/328646746
http://www.canstockphoto.com/stock-image-portfolio/keifer
Also, you can find public domain images, usually shot by the government or military photographers, though not confined to government and military subjects at wikipedia commons. You can find the link at the bottom of most applicable Wikipedia pages. Some of these are of quite high resolution and quality. Just check the usage notes to be sure you can use it for your intended purposes. For instance: I found a photo of Walt Disney for my "It Happened on Christmas Day" trivia countdown there. It was taken by a NASA photographer while Disney was touring the facilities and is therefore government (aka we the people) owned. You can find things like audio clips there sometimes as well. Again, just check to make sure you're allowed to use it for commercial use (or whatever use you intend).
Hope it's okay I (shamelessly) added the landing page to my portfolios on these stock sites' URLs. Please forgive me if not. Also, though my offerings there are mostly landscape, these sites are great places to find people images at a relatively low cost compared to hiring models, getting them to pose exactly like you hoped, etc. One warning: some of these sites have no qualms about posting R-rated type material so be careful out there. Also, make sure the license you purchase covers the precise usage you intend for the file as I don't know how lenient these secular businesses would be with copyright infringement even if unintentional. Hope this helps.