Rag knitting, plastic bag crocheting

Too much fabric? Tear it up and turn it into "yarn" - knit yourself a bath mat - http://www.cocoknits.com/info/tutorials/ragknit.html

The finesse is in joining the strips by threading them through slits, rather than by knotting.

Oh and if you were thinking of cutting up and crocheting plastic bags, do it quickly - they are disappearing (hurrah!) as the grocery stores start to charge for them. See how here and here, for example. (Door mats, anyone? Backpacks? Koozies?) Again, preparing your "yarn" is crucial.
Or branch out into sea creatures - these sinister beauties come from the coral reef "rubbish vortex" project.