I have three dogs and i've been able to get fleas out of my home succesfully by using the natural remedies on this website:
http://www.healthy-dogs.net/fleas.htm


We put table salt all over our furniture, carpets, ect and left it overnight then vacuumed - no more fleas for us! It may be different with cats though, because I don't think they'd let you bathe them in tea tree oil.