This is a collection of web sites that provide stopword lists in several languages.
Ranks.nl provides stopword lists in English, as well as in Czech, Danish, Dutch, French, German, Hungarian, Italian, Norwegian, Polish, Portuguese, Spanish and Turkish.
This site offers further explanations and articles on stopwords.
Mixed-up English and German stopword list within the Ovid database.
Stopworld list of the full text indexing engine Onix.