id,name,dom,xpath:http://darrellgrainger.blogspot.com/2010/03/how-to-pick-identifiers.html
some good topics in this thread from IBM developers:
http://www.ibm.com/developerworks/opensource/library/os-webautoselenium/index.html
Testing an Ajax application with Selenium
How to support Dojo applications
How to build Selenium test with Ant
How to support testing HTTPS websites
How to effectively recognize web elements without ID property
How to handle a pop-up window
How to handle upload/download file window
How to verify alert/confirmation/prompt information