Beamer’s author is Till Tantau. As of April 2010 its development was taken over by a new team. See
https://bitbucket.org/rivanvx/beamer/wiki/Home
for news, discussions, and downloading information. The most recent Beamer distribution may be found there as a single tar archive which includes, among other things, Beamer’s manual and several demos.
Beamer’s manual may be obtained separately from
http://www.ctan.org/tex-archive/macros/latex/contrib/beamer/doc/
although it is safer to use the one that comes with your own Beamer installation because there may be version dependencies.
Norm Matloff at UC Davis has produced a very brief introduction to Beamer; it may be useful if you want to get started in a hurry:
http://heather.cs.ucdavis.edu/ matloff/beamer.html
Charles Batts has written a detailed tutorial in the form of a Beamer slideshow:
http://www.uncg.edu/cmp/reu/presentations/Charles Batts - Beamer Tutorial.pdf
Ki-Joo Kim has created two very nice tutorials that demonstrate many advanced features of Beamer. You can find these tutorials, named beamer_guide.pdf and beamer_pstricks.pdf in:
http://www.geocities.com/kijoo2000/beamer.html
The link given above seems no longer to exist but my own copies of those tutorials are available here:
beamer_guide.pdf beamer_pstricks.pdf
This is only tangentially related to Beamer: If you are using Xpdf to view PDF files, then you may be interested in Stephen J Eglen’s wxpdf script. It’s a perl-based front-end to Xpdf that watches a PDF file and updates the Xpdf window whenever the file changes.
While there, have a look at the link Notes on extending emacs. This may be useful to you if you are an emacs user.