I've tried out some of the kinder-friendly math apps and the results have not been all that good...
Here are some that wound up in my discard pile:
Piggy Math - a pig walks around and things fall into a basket on his back. If he catches them, a voice counts. You can't see how many have been collected so there is no visual correlation. This app does not meet our criteria for classroom benefit. We can do this better with math manipulatives and hands on activities.
Monster Squeeze - I was optimistic about this app since it comes from Everyday Math. The intent is nice, practice with comparing numbers. However the intent does not match up with the game. A kindergartener will enjoy tapping the monster's tentacles to move him, but the numbers piece gets lost. It ends up more silly pointless game and less math practice.
TanZen Lite - Too sophisticated for kindergartners or any early elementary students. Requires adept and very specific manipulation of tan gram pieces in order to solve puzzle.