Let It Roll is a multiplayer game where you roll 5 dice and keep score.

The phone will save your game so even if you quit or turn the phone off it'll remember where you left off.  The Kudit site says:

Yahtzee-like dice game that can be played with any number of people. Works in portrait and landscape modes!

Beat this game by jumping the marbles over each other until they’re all gone. You can move them into open spaces either horizontally or vertically.  The site instructions say:

This game is based on an enjoyable board game that uses marbles arranged in a triangular formation. The game is played by jumping adjacent marbles into an open space either horizontally or vertically, removing the marble jumped over. This particular version is my favorite and I have spent hours playing it and I hope you do too.

Sarkscape, the creators of Ninja Ropes and Block2Lock have created a great, asteroid-like game called Mass Defense.  In the game your objective is to make sure no planets hit yours by shooting at the and redirecting their course.  The white meter on the top left indicates the amount of ammo you have and the red bar is health.

I really like this game and played about 5 rounds straight just now.  I'm finding the key is to let your ammo build up as much as possible and try to get your shots to bounce from planet to planet so you get more bang for your shot.  You'll definitely get hit at some point so make sure the small planets hit you and not the big ones. 

If you're looking for a fun, simple, straight forward game that's addictive this is absolutely it.  Monkey and Banana is easy but challenging at the same time since you really have to time your jumps.  The controls are easy - just jump from side to side eating the ripe bananas and avoiding the rotten ones.  You need vitality to jump though so keep and eye on the meter up top and make sure to eat enough ripe bananas to keep you jumping.

A screenshot of the instructions is below.

Help Sakura fight monsters, spiders, zombies and more! This is a lot of fun for anyone who play the old school Castlevania games.  DS Effects has a bunch of games but this is definitely one of my favorite. 

The key with this, and a lot of DS Effects games is to not get discouraged.  The gameplay is quick and pretty difficult but if you give it a few tries you'll get better and will end up having fun.  Just be patient and let yourself die a few hundred times....you'll get the hang of it. :) 

Sarkscape Games has created a sequel to the fantastic original Ninja Ropes.  This is one of the better games created that fully integrates all the functionality of the iPhone.  The game instructions say:

Ninja Ropes Extreme is a sequel to the famous Ninja Ropes game. Now you will fight against gravitational anomalies.

New gameplay, new challenges and new gaming experience. Show your best in the ninjas' secret knowledge and be first in the online top 15.

This is a must play. 

Under Clouds makes consistently the best games for the iPhone/iTouch and Penguin Attack is no exception.  This is a great, addictive game that is difficult, slick and definitely not like many others.  Your goal is to slide your penguin(s) across the ice to bump various bad guys off your ice block and into the water.  But watch out because you trade off moves and they're trying to knock you into the water as well.

As the game becomes more difficult new characters will appear.  A screenshot of the help menu is below.