Sweat bee

Insects can be extremely difficult to ID. For instance, as you may know, some dragonflies are easy to figure out. But some closely related species require the insect to be inhand and their claspers to be examined by handlens for definitive ID. In damselflies even dissection of the subject and a microscope may be necessary to determine ID to species level. Nonetheless, it is a wonderful puzzle to attempt and your photo is very good of a very pretty insect.

very cool!

That Bee is a beauty.

For an ID, I'd suggest looking at the metallic sweat bees, probably in the genus Agapostemon. See this page for more information: http://bugguide.net/node/view/7997/bgimage. There are many sweat bee species and lots of them look very similar. Perhaps you may want to label the sighting simply as Sweat Bee and list the scientific name as "genus: Agapostemon. If you want to see how difficult it is determine to the species level, see the discussion at http://bugguide.net/node/view/478729/bgimage and other pages. Very nice photos by the way. Macro work is a lot of fun and you never run out of subjects.