Hammerhead is a web site coverage, HTTP load generator, HTTP benchmarking, and stress testing tool. It has been designed to emulate multiple users from multiple IP addresses at maximum speed (unlike it's interpreted counterparts).
WebMonX is a cross-platform tool which monitors websites for updates and changes. It saves you time and always keeps you up-to-date by periodically checking these pages at set intervals.
AnCaraS is a tool to analyze and characterize web sites. It offers an informetric characterization, a topologic description and an interactive graphs view and manipulation.