I remember years ago, a friend showed me her portfolio of poems, and one really hit me so I picked up the guitar and sang it. A few weks later she turned up with an amended version that she said she'd produced because she loved what I'd done so she'd altered it slightly to make it a better song - and in the process she'd lost evrything that had attracted me in the first place.

If you want to see how poems can be sung without a strict rhythmic framework, have a listen to Brecht's "Holywood Elegies".