With the constant growth of web based content large collections of textual become available. Many if not most professional non-English web sites offer translated webpages to English and other languages of their clients and partners. This are usually professional translation and are abundant. We call this Hidden Web. We intend to present possibilities, problems and best practices for harnessing such aligned textual corpora. Such data can then be efficiently used as a translation memory for example as help for a human translators or as training data for machine translation algorithms.