about

• BackPAN is nothing more than an rsync'ed mirror of funet.fi without the --delete option active. There may be more than one public BackPANs (backpan.perl.org and backpan.cpan.org used to be separate, for instance). And there are still (at least one hopes) several private copies of BackPAN being made.
• Publically-available BackPANs:
  • backpan.perl.org
  • mirrors.develooper.com/perl/backpan/

creating a basic index, since BackPAN has none

• http://www.astray.com/tmp/backpan.txt.gz is an index that's kept up to date
  • although it is labeled "tmp", it is codified in several long-standing tools: Parse::BACKPAN::Packages, BackPAN::Downloader, ...
    
    
• BackPAN::Index — build a basic index, since none is found on the BackPAN website
• Parse::BACKPAN::Packages — build a basic index, since none is found on the BackPAN website [git]
• Module::CPANTS::Generator::Backpan — scans through a BackPAN mirror and generates the number of releases a distribution has made

downloading

• instructions on how to use rsync to get it
• BackPAN::Downloader
• git-backpan-init

after downloading

• CPAN::ParseDistribution — looks inside a BackPAN distribution tarball, and tells you: what modules, what module versions, distribution name, distribution version
• CPAN::Metadata::RDF — generates metadata about CPAN/BackCPAN modules in RDF format

other BackPAN-related modules

• BackPAN::Version::Discover — tries to determine exactly which CPAN/BackPAN distribution release each installed module may have come from

other websites that aren't EXACTLY the same as BackPAN, but are close in mission

• historical versions of Perl
  • mirrors.develooper.com — includes sporadic versions from v1.0 to v5.000, and everything from v5.000 on up
  • BackPAN has some very old versions of Perl on it, but not all of them are indexed/recognized because the older packages are non-standard.
    • my own attempt to locate them by filename search
    • search.cpan.org — includes v5.003_07 and up
    • beta.metacpan.org — includes sporadic versions
• other interesting stuff at mirrors.develooper.com/perl/