WATCH THIS !!!! ( I would embed this , but the SUCK forum SW SUCKS HARD !!!





http://www.youtube.com/watch?v=qHBVnMf2t7w&feature=player_embedded

All of the techniques described so far are great ways to come up with different progressions and get finished songs.

Something I also found very thought provoking and helpful is to listen and dissect other songwriters material.  I especially like the chording techniques used by John Lennon and how he takes the same melody and will actually play through a different chord progression underneath. 

That is a way of working through a song differently that the standard way of thinking.  Sometimes this opens up the idea for working to a chorus or bridge differently than you originally thought.

Also, collaborations with another songwriter will sometimes help with regards to chord progressions as well.  When I work with someone else, I will sometime hear a different way to progress through the section and present that to them.  If successful we sometime take the song in a different (sometimes a success) way to conclusion.

Just some thoughts.

And don't forget drugs... :-)