Even those who work at Google are often surprised at what they find when they visit their Google Dashboard. It's a good idea to check in on what Google has on you regularly, for reasons both tinfoil-esque and practical.
Ars Technica's Jacqui Cheng visits Google's Chicago office and comes out with a newfound appreciation for just how much information, personal data and settings Google offers to all its users — and how much we leave behind:
Who knew that I still had an Orkut account? I didn't until today. I also have a Google Health account from 2008 with no records (aside from my height and weight), 15 public maps in Google Maps, and 3,000 archived Google Chat conversations. If I had Web History turned on, I would also be able to see every single Google search I have ever made, line by line-and it's a good thing I don't, because there have been a lot of embarrassing ones.
It can be a bit overwhelming, for certain, but the Dashboard offers a way to get to all of it, either directly or through Settings page links. Beyond just making sure there's not as much of your past thoughts lurking online, changing things like your default Google Checkout address and wiping out old credit cards could save you some frustration down the line too. Add a Dashboard appointment to your calendar and repeat it yearly.
What Google knows about you and how to tweak it [Ars Technica]