1.
Google search the most popular and powerful searching tool. And remember you can use "show option" for more better results.

But you can use Google search like a tool for study languages. If you don't know your sentence is correct or not, you can type in Google with "", but of course the best way is native speaker checking it for you, but sometime , you don't have time let's try use it or for figuring out words based search results. Very useful, I often use it.
If you are interested in Google search about this topic,
more info2.
YouTube you not only can search music, animation , you can also search the guide for using some tools like making blog, the function of websites...or everything you want to know. There are tons of people making videos for guiding.
3.
Google picture,
Picasa,
Flick...for more picture search.
4.
Yahoo search,
Bing let's try others searching tools, too.
And finally, if you visit any websites, if they have search bar, let's always try using it because maybe you can get amazing results.