If you are learning a new language, you need all the practice you can get. I can tell you from personal experience that the easiest way to get this practice is by seeing the language in real-life situations. If you can't get to a Spanish-speaking country, the next best thing is to read newspapers, watch videos and surf the net, all in Spanish. Barra de Español is a Firefox add-on designed to help you do just this.
Barra de Español is quite subtle. It appears as an attractive toolbar, and a few functions are added to the context menu. The add-on allows you to search for words on either WordReference.com or Forvo.com (for pronunciation). You search by typing in the box on the toolbar, or by highlighting the word and right-clicking. If you use a non-Spanish toolbar, don't worry. Barra de Español allows you to add accented letters and punctuation directly, either by clicking or using a simple shortcut.
Barra de Español's other tools are direct access to videos, news and reference sources in Spanish, which the tool opens in a new tab. The default selection is interesting and international, so you won't get bored easily. Unfortunately, Barra de Español has no configuration options, which means you can't change the dictionary used, for example, or the newspapers listed. Other than this, Barra de Español is a useful tool for people who are serious about learning the language.
Barra de Español adds useful functions for learners of Spanish.