Here's the PLUGGGG (TM) method. Try it and see what happens for you!

Step 1). Determine # of chords you want in your verse, chorus, and bridge. Write a bunch of chords you know (or want to learn) on small cards and put in the hat.

Step 2):Draw chords from a hat. Voila - chord progression!

Step 3). Open The Grateful Dead Lyric Book. Each member blindly select a word - Instant Song Subject!

Step 4). 2 Minute Lyric Drill (vocalist may have to call an audible and reshape to fit)

Step 5). Work out the basic shape of the tune, where changes come, and maybe even an ending. Maybe.

Step 6). Roll Tape and capture the birth of a song.

So far, we're 11 for 11 with this formula, including twice in front of a live audience.