Shortcut to search multiple websites in Firefox

Firefox allows you to search a website using a keyboard shortcut. This function is known as quicksearch or "keyword search". MozillaZine Knowledge Base describes how to create quicksearches for a single website.

You can create a single quicksearch for multiple websites using JavaScript, as described in this forum thread. I made a quicksearch for three music stores: Amazon MP3 store, 7digital, and Yahoo! audio search. To use it, go to the Properties of an existing quicksearch, and replace the text in the Location field with the following code:

javascript:void(window.location%20=%20'http://www.amazon.com/s?initialSearch=1&url=search-alias%3Ddigital-music&field-keywords=%s');void(window.open('http://www.7digital.com/Search?search=%s&searchtype=global'));void(window.open('http://audio.search.yahoo.com/search/audio?ei=UTF-8&fr=sfp&p=%s'))

Each search will open in a new window or tab, depending on your Firefox configuration.

P.S. The keyboard shortcut to jump to the address bar is Ctrl-L in Windows, and ⌘-L on a Mac.