Want to run your best half marathon ever?

Run with thousands of other women — but do it on your own turf and on your own time. Nike's newest, niftiest challenge is the Nike+ Women's Half Marathon on October 21.

That's the day 20,000 women are running in San Francisco for the world's largest women's marathon. You can support the runners wherever you live by doing Nike's virtual half marathon on the same day, using your Nike+iPod kit. The virtual race costs $55 (money benefits the Leukemia and Lymphoma Society). Run the 13.1 miles with your Nike + iPod and download your results, and you'll get a Tiffany finisher's keychain, a finisher's shirt, and bragging rights.

Go to NikePlus.com to register and to find training programs and running partners.

What Do You Think?