The world's largest free software development site. Around 80000 -
eighty thousand - projects are hosted here, in different stages of
development. It's nearly impossible not to find what you need.
And you can help the authors with their development in many ways!
This is a sister site of SourceForge (above), which specializes in
announcement of released software packages for *nix platforms, such
as Linux, Solaris, etc. Around 40000 packages are registered.
No Windows packages here.
This is a 'daughter'-site of gnu.org, and hosts many (about 9000?)
development projects. It is similarly intended as Sourceforge, but
completely ad-free. In my opinion, slightly less appetizing because
of a policy on (too-) simple HTML. That does not make the projects
less valid! It's just more difficult to convince the users using
plain old static HTML.
An announcement site with similar intentions as Freshmeat - though
much more advertisements. This site also hosts more than 40000
programs, but these are mainly Windows, and many of them are
are shareware.
A big problem with TUCOWS is that programs are updated according to
payments. So, commercial programs (which spend money at TUCOWS) are
more recently updated than shareware, or, even slower, open software
which does not have the funds. Last time I checked, waiting times
for more than 180(!) days were normal for non-paying programs to
be updated.