As you might know or not, DZone weekly publishes free "Refcard" cheat sheets on various technical matters.
This week's is one that Yehuda Katz and I put together on jQuery selectors.
You need to sign up, but membership is free and there are also some great articles posted on DZone as well. (A recent one on "Is Tomcat an App Server?" is in answer to a common question posted here in the Tomcat forum.) Link to DZone Refcard Page