chucklivesoninmyheart:
Here's my advice. The best way to get through creative 'dry-spells' is to do some cheap home-made recording. Basically, if you have a 4-track or even a crappy soundcard with a mic input, you're in business! Often, if I don't have any ideas, I will sit down and make something up on the spot. The reason recording your ideas is so crucial is because if you come up with something that sounds half-decent (but not necessarily 'great'), once you multi-track it, you might discover a real gem! In other words, if you're having trouble coming up with riffs, sometimes simply recording yourself and listening back can help prompt more ideas. Do not set out with any goals. Just try and make stuff up on the spot; go out on a tangent. Try ideas/riffs that you normally wouldn't consider. The best riffs are (more often than not) discovered by accident.
Hope this helps.
Matt