I just ordered our emergency birth kit from http://midwifesupplies.com
I'm sure others will have great ideas of must-haves, but I can't think of too much off the top of my head. I remember we bought shower curtains at the dollar store to protect the couch etc., and that really worked well. We cut up an old towel for perineal compress (with hot water, during later labor & delivery), and that helped a lot. Hmmm, otherwise can't think of anything out of the ordinary to suggest!