In Firefox, I use the InstantFox add-on to combine address bar and search bar into one item – like in Google Chrome.

But even without this add-on, Firefox allows you to restrict your search by adding a character in front of the search terms, like so:

Notice the * in front of the search term bugs. This restricts the search to bookmarks.

Here’s a list of the most important restrictions:

All these shortcuts can be edited in about:config under browser.urlbar.