I use the i phone, but i think the apps are available on most platforms now.
AeroWeather is what it says, and is quite handy, as you can monitor just about any field in the world. PilotWiz is good for all these calculations you have to do to go flying. V-Cockpit lite is a bit of fun!
Many apps are available free in a 'lite' form, but if you want the full boona you will have to pay.