Hi kbrassel - Lots of good advice in previous posts, especially about jotting down ideas or observations. Always have a piece of paper and a pencil in your pocket.
Even if you don't seem to be making progress on songs that are underway you still need to keep your eyes and ears and imagination open for ideas. Gather these bits together and have them on hand because they become the raw material for flights of fancy.
Keep working on stuff you have already started - but also start some other stuff too. Don't feel like you must 'finish' something before you can start on another idea. Having several ideas working seems to help me. Also, work at song writing every day (whether you feel like it or not).
I think every creative person has dry spells - don't let it bug you too much. Just to shake things up a bit, try writing limericks or haiku or anything that will be a change of pace. Go for a long brisk walk and let your thoughts wander (but have that piece of paper & pencil with you).
"That darn Pythagorean Comma thing keeps messing me up!"
[url]http://en.wikipedia.org/wiki/Pythagorean_comma[/url]