The Music Translator is a resource of sheet music: arrangements, transpositions and transcriptions for various instruments. This page is located at M U S I C A N E O
You can find here a lot of arrangements for string quartet, string trio and an original composition "Black sheep - White sheep" Suite for violin, viola and cello.
A very interesting arrangement made by Mladen Spasinovici is "Pictures at an Exhibition" by Modest Mussorgski for string quartet.
You also have the possibility to see first page as a preview of every sheet music you will find on The Music Translator page.