A few XPath links to make YQL and HTML scraping easier.

quick and basic
http://www.w3schools.com/XPath/xpath_syntax.asp

great resource for detailed string functions
http://oreilly.com/catalog/xmlnut/chapter/ch09.html

quick list of all of the functions in xpath
http://www.w3schools.com/xpath/xpath_functions.asp

great example of more sophisticated function selectors
http://www.eggheadcafe.com/articles/20030627d.asp

multiple attribute
http://www.coderanch.com/t/128329/XML/XPATH-selection-based-multiple-attribute

fun with concat
http://blogs.sun.com/rajeshthekkadath/entry/xpath_searching_for_a_text

http://www.xml.com/pub/a/2002/08/14/xpath_tips.html?page=3