These are projects I haved worked on for the Metalink Project.

Metalink Checker - A Python script to check metalink files and complete a basic download, also converts between v3 and v4 (IETF RFC)

DLApplet - A browser applet for faster and more reliable downloads

Metalink Crawler - A Metalink search engine

SFMetalink - Converts sourceforge.net download URLs into Metalinks

Apachegen - Converts metalink files into Apache directives to implement Metalink HTTP Headers

Conversion Web Service - Converts Metalinks between v3 and v4 using XSL

IETF RFC - The latest Metalink spec

Transparent Metalinks - Allows for use of the same link for a normal download client as well as a metalink aware client

Metalink Headers RFC - A spec to integrate metalink information into HTTP