KeepWiFi

KeepWifi ensures your WiFi stays on, even when your phone is in sleep mode.

Annoyed by observing your WiFi connection switches with 2G/3G when your cell phone takes its pause?

This service will keep your Wifi connection on air, even if your phone's screen goes off.

There is also an extended version (KeepWiFi locale) with Locale Plug-In and you can use to it say thank you.