February, 2009 - Latitude: Adding a social component to Google's popular Maps seemed like an easy way to compete with FourSquare, although today it's become perhaps best-known as a for those obsessed with keeping track of their own movements. While Latitude never caught up with FourSquare, I'll be shocked if its features don't become key components of Google+.

May, 2009 - Google Wave: If there's any reason to believe that Google+ might flop, it's Wave. Meant to be an everything application, Wave was supposed to revolutionize real-time collaboration while incorporating social networking, well... kind of. It's actually a little hard to describe, and it turns out it was hard to use as well.

August, 2009 -- Social Gadgets for iGoogle: Google reprised the social widget concept first seen in FriendConnect with these small games and collaborative apps that could be added to users' personalized iGoogle homepages. I was surprised to find some of these gadgets still on my iGoogle page, which I haven't visited for well over a year now.

February, 2010 - Google Buzz: Google's answer to services like Digg and the epidemic of link-sharing on Facebook and Twitter never caught fire, but could get a second life on Google+.

February, 2010 - Aardvark: This social answers site had a small cult following long before Quora. Google purchased it and moved it to Google Labs, where it has languished, perhaps waiting to be folded into Google+?