Sprint already won the race to market with its AIRAVE, but it’s Verizon Wireless’ Network Extender that seems to be the better overall deal. For those unaware, a femtocell is — for all intents and purposes — a miniature cell tower that connects to your broadband Internet. Once installed, it gives you impeccable at-home coverage by routing mobile calls that originate in your home through the Internet. Sure beats climbing up to that one window in your attic to eke out a single bar, doesn’t it?Starting this week,