Linux MultiMedia Studio - LMMS

LMMS is a free cross-platform alternative to commercial programs like FL Studio®, which allow you to produce music with your computer. This includes the creation of melodies and beats, the synthesis and mixing of sounds, and arranging of samples. You can have fun with your MIDI-keyboard and much more; all in a user-friendly and modern interface.

Features
    * Song-Editor for composing songs
    * A Beat+Bassline-Editor for creating beats and basslines
    * An easy-to-use Piano-Roll for editing patterns and melodies
    * An FX mixer with 64 FX channels and arbitrary number of effects allow unlimited mixing possibilities
    * Many powerful instrument and effect-plugins out of the box
    * Full user-defined track-based automation and computer-controlled automation sources
    * Compatible with many standards such as SoundFont2, VST(i), LADSPA, GUS Patches, and full MIDI support
    * Import of MIDI and FLP (Fruityloops® Project) files

Download:
The following binary-packages are currently available:

    * Windows 2000/XP/Vista - here
    * Ubuntu 8.10 - here
    * openSUSE 11.1 and 11.0 - here