wiSync 

A free, completely transparent, WIFI synchronization assistant for your Android phone. Save Battery. Save Money. Save Time! Even better, WiSync doubles as a Locale plugin. If you're a Locale user, WiSync is a must have application. Automatically enable and disable synchronization based on your WIFI connection status. WiSync can save money for those without unlimited data plans, out of the country, or when simply data roaming. WiSync does not interfere with independent synchronization efforts and can be easily disabled.