Once again, as I searched through my old stack of Guitar World Magazines looking for inspiration I happened to find this article by John Petrucci of the band Dream Theater. I'm still not a fan of his band but the more I read stuff by him and see his tutorial videos online, the more I have respect for him as a guitarist.
In the article John talks about permutating one simple riff and turning it into several cool ideas. He provides the following advice to those who may have fallen into a musical playing or writing rut. While tinkering around with a riff and still retaining its original melodic and harmonic intent try:
1) Play the riff an octave higher or lower
2) Harmonizing it either diatonically with intervals such as thirds or sixths, or with parelled power chords (root-fith)
3) Add different effects to the riff
4) Split up the notes in the riff and have a different guitar play each section
5) Change the riff's time signature
*CLICK ON THE ARTICLE TO ENLARGE IMAGE*