WolframAlpha is not just another search engine - in fact it's computational knowledge engine: it generates output by doing computations from its own internal knowledge base, instead of searching the web and returning links.

Examples by Topic of what Wolfram can do can be found -:-Here-:- and in the youtube video's below.

You can choose your Wolfram background by choosing your settings -:-Here-:-

There are many Wolfram downloads available from toolbars to Dashboard Widgets for your Mac and yes there is even an app for WolframAlpha!

Have fun!