I have used Diatomaceous Earth as a natural flea control many times with great success on both dogs and cats. It is very fine white powder almost like talcum, but is odorless and very easy to use.
DE comes in food grade or garden grade, and the food grade is needed so that it is totally safe to put directly onto the animal. I used a plastic ketchup container I bought at Wal-Mart for 99 cents because it has a cone shaped end that lets you "puff" the powder under the fur next to the skin. The fleas only need to walk through it to be affected, so I used it around the neck and around the tail of the pet. Works great.
The only downside I found is that the fur becomes fairly thick after using the DE for awhile, so getting a flea comb through was a little tougher. But within a week of using it, fleas were gone.
I order mine online in 5 pound quantities which lasts for a long time.
