Complete Text of Euclid's Elements with Java animations is at the site of David E. Joyce at Clark University. His home page also has more history, compass geometry, and more.
Byrne's 1847 Edition of Euclid, that uses color instead of letter labels, can be found on the web, thanks to groups at UBC.
EUCLID'S GEOMETRY: History and Practice is produced by a classicist and has a lot of history for the last two millenia regarding Euclid and the Elements.
Time Line of Greek Mathematicians. When did all those Greeks live?
History of Geometry on Dan Sunday's site has many scholarly links and bios, including links to the MacTutor Math Archive at St. Andrews University, Scotland..
Axiomatic Systems for Geometry by George Francis goes into quite a bit of depth about axiom systems for plane geometry.
Birkhoff's original paper, A Set of Postulates for Plane Geometry, Based on Scale and Protractor, in the Annals of Mathematics is available at this link on JSTOR (this is only available from computers at the UW or possibly other JSTOR subscribers). The Annals paper has a more sophisticated statement and development than the high school textbook Basic Goometry.