This isn't new information by any stretch, but I was talking to someone today and had to remind them that when creating a web based application, you shouldn't use "id" as a URL variable. Google will not crawl URLs or Links that have &id= in the URL. This is because of the way a lot of applications handle sessions. There are lot of other useful technical and webmaster guidelines to follow when making any web page or web based application. You can find information about the "id" variable, and more at the Google Webmaster Guidelines.