Yesterday I wrote about All Seeing Eye, a free extension for Chrome which lets you search the full text of every web page you've visited. There's actually another similar extension which does the same thing, albeit in a slightly different way.
Deeper History again stores the full text of all the pages you visit, so you can find that page again if you remember a couple of words that appeared on it. Unlike All Seeing Eye, Deeper History doesn't replace the built-in History system, but instead you access it by typing dh followed by the Tab key in the address bar.
One drawback with Deeper History, over All Seeing Eye, is that it doesn't store a thumbnail image of the pages you visit. It does, though, have the added capability to highlight the search term in the retrieved page when you view it. In addition, if you search for a special page called .db it will show you some stats about your database of stored text, and even dump the entire contents of that database on screen. Which is very handy if you want to collect information from a large set of pages (or, of course, if you want to see what someone else has been browsing on your computer).
You'll find Deeper History at https://chrome.google.com/webstore/detail/deeper-history-your-histo/aohg... if you're using the Chrome browser.
As to which one is best, I currently have them both installed while I make up my mind. But the fact that All Seeing Eye attaches itself to the standard Ctrl-H history feature means that this is probably the one I'll use most. But time will tell.