One tool that I have found extremely useful in the past few years is Del.icio.us. This website is a great place to store your favorite websites. Basically you put in the address of a site you want to save, and type in several words, tags, to describe the site, that will help you remember it. So, if you are interested in remembering a site like GMail - you might type in mail, email, google, contacts, etc...
Once you have input several sites you can then search them. You can look at all the tags for say math, or education that you have saved and check out the site. Also you can click on a tag - let's say math - and see all the sites that other people have tagged as math. You can discover other sites that might help you find what you are looking for.
Check out my Del.icio.us site - Patrobyn - Education - here. You can search the tags on the right side of the screen, or you can search the site using the search bar at the top.