One of my favorite sites for Professional Learning Community resources and tools is plcwashington.org. Like Allthingsplc.info from a previous post, this site is not specific to Science PLCs, however, many of the general PLC resources are essential for an effective Science PLC.
Applications for Science Teachers: This site provides a rich clearinghouse of tools, protocols, video clips, etc for creating, sustaining, and reinvigorating an effective collaborative group of educators. Probably most useful for a teacher leader who is facilitating a PLC. Dig in- there is lots to find here.