Try these sites:
a)
Freshmeat.net
Freshmeat maintains one of the largest directories of open source Linux, Unix, and cross-platform software.
b)
Ibiblio.org
Ibiblio archives more than 171 gigabytes of Linux programs and documentation freely available for download via FTP and/or WWW access.
c)
LinuxApps
This is a comprehensive directory of Linux downloads.
d)
SourceForge.net
This is one of the largest repositories of open source code and applications available on the Internet.
Must read this page
www.linux.org/dist/download_info.html
Do let us know, if it helped you!!
Do googling also!