Gmail
Tyler Cowen at Marginal Revolution posts this interesting piece of info about the consumers surplus from Google's Gmail:

Google will be offering its Gmail service for free, but right now supply is limited. Not surprisingly, a market in the accounts has arisen, check out this ebay listing. I have heard that some accounts have gone for as much as $150.

It's actually pretty useful. When I heard that I was being let go, I had a bunch of personal stuff on my work PC that I needed to get like pictures and stuff and limited time to do it. So I just emailed everything to my gmail account, which would not have been possible for any of my other email accounts.