Something I like to do is poke around the dusty halls and closets, so to speak, of search engines (yes, I'm kind of a search nerd). You can find all sorts of interesting things this way. One of the more useful services I've come across are "dashboards", so to speak, of each search engine's properties, sites, tools, and services, all in one incredibly convenient place for easy access. For example:
Yahoo is one of the world's most popular online destinations, and they offer a lot of peripheral services that can be found all in one place at For Yahoo! Searchers. A couple of interesting sites that caught my eye: Creative Commons Search, Video Search, and Local. This is just Yahoo's search services; you can find all of Yahoo's services at Yahoo Everything, an alphabetized smorgasbord of what Yahoo offers online.
Google offers what they call Everything Google, divided by subject: Web, Mobile, Media, etc. Quite a few here that we're all probably familiar with, and quite a few that we're not, including SketchUp, Product Search, and Fusion Tables.
Bing at a Glance gives you a nice visual display of Bing's services. I'm going to spend some time today with Online games, Events, and Recipes.
Not a search engine, but you can get a look at all of Amazon's many, MANY departments with the Overview.
A few more hubs you might be interested in