Internet History Sourcebooks Project
Fordham University: Medieval Sourcebook: Vasari Lives of the Artists
This wonderful site from the Fordham University indexes selections from the great writer Vasari and his major work on the lives of Renaissance artists. The text is translated into English and a bibliograpy is provided for further research.
Other
Life of Masaccio
This site displays some of Masaccio's most famous works. There is a brief commentary on each masterpiece and the clip art is thumbnailed.