If I enable all of the repositories in my sources.list I have almost 25000 packages.
If there is something you can't seem to find you can always search www.apt-get.org
or search freshmeat.net
Like everyone else has said you are better off finding a distro that meets all of your needs rather than worrying about which has the most packages.
SuSe comes with a ton of apps also. As does Mandriva.
You can always compile from source or use alien to convert a package to whatever form the distro you choose uses.