chklinks is a non-threaded Perl link checker. It helps finding broken links on your website. It does not raises many simultaneously connections for its job, run out of the resources and crash your system in a moment.
Like social boomarking, allows users to share their bookmarks online. Like wiki, anyone can freely edit links. Export / Import boomarks with your browser. Many other features: RSS and Atom feeds, URL check, popular categories, XLIink, ...
LCat is a php/mysql cataloging system for hyperlinks, intended for use on websites. It is build around a set of objects providing the basic functionality and complemented with a set of scripts and templates to perform communication with the user.