Identifies and ranks subfamily-specific binding sites in proteins by functional significance. pocketZebra is a web-server that can be used to annotate functional and regulatory (allosteric) sites in protein families. It permits to design novel selective inhibitors/effectors. The server provides on-site visualization of the results as well as off-line version of the output in annotated text format and as PyMol sessions ready for structural analysis. It also can be used to study structure-function relationship and regulation in large protein superfamilies, classify functionally important binding sites and annotate proteins with unknown function.