Hi,

This is a feature request for Metalink support with curl. Metalink is
an XML format for listing the multiple ways you can get a file along
with checksums. Listing multiple mirrors allows failing over to
another URL. Checksums allow a file to be automatically verified, and
repaired if there are errors in transfer. You can also add multiple
files to a transfer queue and do other cool things w/ the metadata
like only use domestic mirrors. I'm putting up a bounty for this
feature, please contact me if you are interested. This would probably
be a separate program that uses curl.

Metadl is a NSIS plugin that downloads with libcurl and uses the
information in metalinks.

There's more info at:
http://en.wikipedia.org/wiki/Metalink

Here are some examples in use. Metalink is mostly used for ISO
downloads, but also for other things...
http://en.opensuse.org/Released_Version#Metalink
http://community.dofus.com/mmorpg/download/full.html?game_id=1&type=metalink
http://curl.haxx.se/download.html
http://eric.jain.name/2007/03/07/metalink-for-uniprot-rdf/
http://wubi-installer.org/ (uses Metalink to repair ISO download)

There are currently about 13 download programs that support Metalink.
aria2 ( http://aria2.sourceforge.net/ ) is the closest to curl, it's a
CLI app.

-- 
(( Anthony Bryan ... Metalink [ http://www.metalinker.org ]
  )) Easier, More Reliable, Self Healing Downloads