Chrome: We've all been there once before. You're doing a bunch of research, find a really useful page, and forget to bookmark it, making it very hard to find later. SeenBefore fixes this problem by letting you search only your recently visited pages on Google.
Sometimes, searching your browser history can help, but I find that it rarely finds what I'm actually looking for. SeenBefore just adds a new option to Google's sidebar, searching the title and text of web pages you've previously visited, helping you find that page in record time. It only works after you've installed SeenBefore, though, so you'd have to install it now to use it in the future -- you can't install it and then find pages you visited a few days ago. It even works across computers, so you can search on your laptop for sites you visited days ago on your desktop.
Of course, this means SeenBefore has to actually track your online activity itself, which doesn't sit well with a lot of people. It's worth noting that SeenBefore doesn't track your activity on HTTPS sites or while in Incognito Mode, and all information is sent to SeenBefore's servers securely. You can also disable it in 2 hour intervals, which is nice. It that isn't OK with you, you'll have to stick with the traditional history search, but the rest of you can sign up and try out SeenBefore by hitting the link below.
SeenBefore is a free download, works wherever Chrome does.