Over the years, the best way I've found to shake a song loose from the quicksand is to do something mindless, an activity where muscle memory takes over -- driving, walking, ironing, gardening (but in silence, without the radio, TV or iPod).
Motor activity can free the subconscious mind -- which is where all great writing is born. With the intent of meditating on your work in progress, put your conscious mind to the task of something mundane while letting your subconscious ramble, taking mental notes on the ideas that might be valid. Almost every time I walk the dog, or take a drive with a song in midstream, I make some good progress.
Here's to inspired writing by all...
Rand Bishop
songwriter/producer/author - Makin' Stuff Up, secrets of song-craft and survival in the music-biz
www.makinstuffup.net