I am finding that rhythm really inspires me in composing. Today, instead of fiddling with notes and chords to figure out what I wanted in one section of my second piece (the arbitrary method I've been using), I drafted five bars of rhythm and afterwards filled out the rhythm with actual pitches. It really sped up the process for me.
I suspect that it may be my poor aural skills that makes this such a good option as a method of composing for me. I am very strong in rhythmic dictation and notation and very weak in the melodic and harmonic areas.