No. There are "natural" flea killers sold in pet stores, but they are based on the same chemical that all the others are. Make sure you double-check the safety of anything you use, because some, such as Frontline, are bad for rabbits.
The best I know of is from pyrethrum daisies (the pink or red ones with yellow-orange middles). Although, you'd have to grow it. Good thing, though, is that the very chemical the flowers make is used in most natural flea treatments. Just look for pyrethrin as the main active ingredient (not permethrin or prallethrin, which are the synthetic versions).
"Billy the Exterminator" uses pyrethrin. I use a lot of garlic and various "volcanic" hot sauces and peppers--I'm pretty much flea and mosquito proof, but I doubt a rabbit would thrive on the stuff I eat.
haha as soon as i see the pyrethrum comment billy was the first thing i thought of. and his voice going its from the crushed flowers of the Chrysanthemum. like he says every time he uses it. thanks all. i was hoping there would be a non chemical way to do it (herbs, things along that line) but i guess i will be going to buy some advantage