Jumping spider (Phidippus johnsoni)
This friendly jumping spider spent most of his photoshoot scampering around trying to investigate everything around him all at once. It wasn't easy to convince him to face the camera. Not that it did much good when he did - he would often leap straight at the lens before I could shoot! Maybe he was trying to make friends with his reflection.
Jumpers have superb vision and are extremely curious. If you put your hand near them, they will often hop on for a chance to explore.
Members of the genus Phidippus are notable for their large size and bright, iridescent chelicerae (jaws). P. johnsoni have a red (sometimes orange) and black color scheme to mimic certain velvet ants. Velvet ants can deliver very painful stings, so it benefits the comparatively defenceless spiders to look like them to fool potential predators.
More shots of this fellow on BugGuide:
http://bugguide.net/node/view/795690/bgimage
And a shot of his stunning chelicerae on Flickr:
http://www.flickr.com/photos/kyrontf/9177472604/