When I can't remember the URL site I just search for it quickly in Firefox which is quicker than trying to remember the address. Today I needed to go to "Google Groups"n:http://groups.google.com/ but couldn't remember the address, so I searched for it on Google
Guess which site came up first?! Not Google, but their main competitor Yahoo! I guess this just gives Google more kudos because their indexes aren't tainted in their favour.