libmtp: Downstream

XNJB is a Cocoa graphical user interface for Mac OS X for the Creative Nomad range of portable MP3 players and newer MTP players. It uses libnjb and libmtp for low-level device communication.
Website http://www.wentnet.com/projects/xnjb/

Gnomad2 is a GTK+ music manager and swiss army knife for the Creative Labs NOMAD and Zen range plus the Dell DJ devices using the Portable Digital Entertainment (PDE) protocol. It was created by Linus Walleij on a rainy day and has evolved a bit since.
Website http://gnomad2.sourceforge.net/

AmaroK is a full featured music player built for KDE. In addition to managing all manner of audio files, Amarok can transfer files to Apple ipods (libgpod), iRiver ifp devices (libifp), mtp devices (libmtp), njb devices (libnjb), and generic mass storage devices.
Website http://amarok.kde.org/

MTPSync is bais GTK app used to syncronize files/music with a MTP device.
Website http://www.adebenham.com/mtpsync/

Not compiling against recent libmtp releases as of 1.3
MTPDude is a minimalistic application for the use of the libmtp which allows to access new MTP-Based Multimedia devices.
Website http://sourceforge.net/projects/mtpdude

Pulp is a Qt4-based media player that allows for seamless playback and conversion between various audio/video formats. Pulp is runnable on WindowsXP, OS X (PPC), and Linux (x86) platforms. Additionally, Pulp uses libnjb, libgpod and libmtp allowing for the syncing of playlists on external media devices.
Website http://pulp.sourceforge.net

Rhythmbox is an integrated music management application, originally inspired by Apple's iTunes. It is free software, designed to work well under the GNOME Desktop, and based on the powerful GStreamer media framework.
Website http://www.gnome.org/projects/rhythmbox/

MTPfs is a FUSE filesystem that supports reading and writing from any MTP device
Website http://www.adebenham.com/mtpfs/

A ruby wrapper for the libmtp library which implements the Media Transfer Protocol
Website http://rubyforge.org/projects/libmtp/

A python wrapper for the libmtp library which implements the Media Transfer Protocol
Website http://launchpad.net/pylibmtp

Qlix is a small QT based graphical user interface for libmtp to communicate with MTP Basic devices.
Website http://qlix.berlios.de/

A tool for the Last.fm scrobbling of the music you listen in your MTP-capable device.
Website http://sourceforge.net/projects/mtp2lastfm/