Visit this link to look at your search history:
The column on the left breaks it down by Web, Images, News, Shopping, Ads, Videos, Maps, Blogs, Books, Visual Search, Travel and Finance.
What about your YouTube search history? That’s here:
If you haven’t opted-out of “interest-based ads”, this link will display your gender, age language(s) and interests:
Do you remember actually telling Google these things? Probably not. Clever, isn’t it?
If you use GPS on your Android phone, Google collects your location history, indexed day-by-day. Find it here:
The Dashboard on the Account Activity page lists all the services you’re using:
Check the tick-box at the top to get a monthly reminder emailed to you.
If you don’t like them knowing quite so much, try Startpage — Google search results in complete privacy.