Nematodes for fleas?

I've started to use more organic practices in my yard and garden with very good results. Each year I release praying mantis and ladybugs and they seem to have reduced the population of those pesky undesirable on the plants. I've almost completely switched to organic fertilizer but I have yet to try nematodes (a little pricey for me). Several companies seem to believe that nematodes to a good job at reducing fleas. Have any of you folks had any experience with nematodes specifically for fleas who would be willing to share their thoughts? I'd love to see some technical data if anyone could steer my in the right direction.

Thanks