Speaking of paella...

I have a number of friends who don't eat pork. (I also have a lot of vegetarian friends, but I'm sorry, I don't think vegetarian paella is really still paella.) Can anyone recommend a good non-pork substitute for chorizo? Non-pork needs to include the casing for whatever sausage it is; a lot of turkey or chicken sausages out there seem to use pork casings.