A new (to me at least) photo resource popped up just recently…
http://unsplash.com/ – 10 new high resolution, creative commons photos every 10 days; free to use commercially. You might find it easier to browse through the archive. Thanks to Alison Thompson for sharing this one.
Getty Images – Embed Tool
(Non Commercial Use only)
Getty have released 35 million images for use through their Embed tool – useful for blog posts perhaps. This was covered recently on the BBC website. It does come with a bit of a caveat, as you can only use images via their embed code (via an iFrame), and for non-commercial use only.