A few websites are larger repositories about poison ivy:

• poisonivy.us
  • pictures
  • treatments
  • FAQ
• poison-ivy.org
  • identification
  • quiz
• purplebutterflies.com
  • identification
  • identification > look-alikes
  • photos
  • myths
• CDC
• lisashea.com
• other look-alike photos:
  • @identifythatplant.com
  • @about.com (images 15 to 30)
  • @flickr.com

More info:

• TecNu can be used to clean urushiol from skin or clothing.
• There is a prototype dye spray that will hilight where urushiol contamination has happened. [2], although it's in a very experimental phase