‘All you ever wanted to know about green fluorescent protein but were afraid to ask’ could well have been the name of the excellent GFP applications page designed by Wallace Marshall at Yale University. This page is a mine of information on GFP and provides plenty of evidence as to why GFP has become one of the most widely used proteins for cellular imaging. There is even an image of Aequorea victoria, the jellyfish that provides the source of the protein — a useful addition to those lecture slides. The web page features a very clean, straightforward design with clearly marked categories that link to books, a newsgroup and various applications and suppliers of GFP-related technology.