It's great for calculations, conversions, and random information. Examples:

http://www.wolframalpha.com/input/?i=1%2F2+an+avacado http://www.wolframalpha.com/input/?i=1.8TB+in+kilobytes

There are some other cool ones you can use, such as "planes overhead", "satellites overhead"

All that said: I generally think that if I was smarter I'd be able to use it for more stuff :)