I meant: how can I browse CPAN itself to see a listing of all the distributions there, rather than just looking at the listing of modules.
The index file
on CPAN contains
a mapping of all modules to distribution names.
My guess is that most packages on CPAN are single-module packages, and that there far fewer multi-module "distributions".
That's an interesting question. Of the 12,166 distributions
listed today in 02packages.details.txt, 8592 have only
one module associated with them. However, some of
these single-module distributions are older versions of
distributions whose current version
contains multiple modules (eg, look
at Slauth-0.01.tar.gz and Slauth-0.02.tar.gz).
This sometimes means that a module in an older
distribution has been replaced, or perhaps been
made obsolete, by another module in a newer distribution,
but it still shows up in 02packages.details.txt because
it's still registered with PAUSE.