Similar to XEmacs

Pidgin (software)

PortAudio

Premake

Privoxy

PSPP

PulseAudio

Pure Data

PuTTY

Qmail

Raku (programming language)

Ratpoison

Rdesktop

ReactOS

RecordMyDesktop

Rhythmbox

KornShell

Scalasca

Security-Enhanced Linux

Sendmail

Singular (software)

Sodipodi

Sound Juicer

SquashFS

Sway (window manager)

Tcl

Tcsh

Thttpd

TiMidity++