You might want to start by taking a look at the Supplementary Pages for this week...
... and you will also find many other resources online:
The Catholic Encyclopedia provides a detailed biography of Saint Francis online.
Franciscana on the Web provides a comprehensive listing of Saint Francis resources on the internet, along with an extensive list of artworks depicting Saint Francis. Kajetan Esser has provided Annotated English Translations of Franciscan texts. The Fioretti ("Little Flowers") of Saint Francis are available in English online at CCEL.
Another Latin life of Saint Francis is also available online: Beati Antonii Vita Prima seu Legenda Assidua. A list of the various lives of Saint Francis can be found at the Franciscan Experience: Main Sources.
The Internet Medieval Sourcebook contains an electronic version of The Golden Legend or Lives of the Saints as "Englished" by William Caxton in 1483, modernized by F.S. Ellis in 1900. The Ecole Initiative has an article online about Jacobus of Voragine.
