Volunteer Management Software?

ewilts asks: "I've been actively looking for volunteer management software but am consistently coming up empty. The vast majority (by far) is Windows desktop based and typically layered on top of a Windows database engine like Access or FileMaker. I'm specifically after something web-based (Linux/Apache) since there is no centralized volunteer office and the volunteers have systems including Windows 95, Macintosh, Linux, and everything in between. So far, eBase seems to be best solution, being open-source but it's Windows-centric, not web-centric. Any pointers to low-cost or free software to help manage a couple of hundred volunteers would be greatly appreciated."