Lingro, founded in 2005 by Arthur Jank, is a popular collection of translation dictionaries for the web. The dictionary enables you to browse your favorite sites normally, and displays a popup translation dictionary when you click on a word.
The Lingro site enables users to browse, edit and share definitions and translations across many languages. The service currently supports about a dozen languages, and several times as many language pairs. English <–> other languages are well covered, as is Spanish <–> other languages.
The service is quite simple in how it works. You simply browse a site by first going to Lingro and entering the URL, then whenever you need help with a word, you click on it to trigger a popup with possible translations.
The service is a great fit for people who have basic proficiency in a new language, but need help with vocabulary. This tool, when used to read content the person is already interested in, is a fun and effective way to learn and memorize vocabulary without having to juggle a separate dictionary or computer program.