OpenID

I probably would use my Google account to open other accounts as it would be easier than the proliferation of login and password details which I have now, including the various accounts I opened for 23Things, many of which haven't been used since (I have to confess). I also have various accounts such as abebooks which use my home email address and others which use my work email. The only ones which use my Google account are the blogs so that's probably not the best use of Gmail and does mean I'm keeping track of quite a few passwords, even if I have used the same one for several accounts where security doesn't matter.