NOTE: Farkle Dice was given away one day on Amazon App Store.
Farkle Dice is a very simple game of chance with some strategy involved. The rules are simple, and you can actually buy the physical game (with real dice) in some B&N stores (that's Barnes & Noble). This is the Android virtual version, with AI players.
The rules are simple, and you will have a hard time beating even the regular "Steady Sam" AI until you figure out the strategy on how it should be played.
Graphics are simple, and typical game only lasts a few minutes. So you can slam a quick game in.
Is it worth money? I don't know. Depends on how much ad you tolerate. Give the free version a try, at least.
http://www.appbrain.com/app/farkle-dice-deluxe-(ad-free)/com.smartboxdesign.android.farkle.dice (paid version)