Rebrickable supports OpenSearch. What does that mean? Well, you can make use of this feature to do a quick LEGO search directly from your search bar.
For example in Chrome (other browsers have varying support for this feature):
Start typing Rebrickable into the address bar, and once the suggestion changes to rebrickable.com hit Tab as prompted. This changes the address bar into a search box. Type what you want to search for and hit Enter. This goes directly to the Rebrickable search page for that term.
A nice little shortcut :)