There are several from Magmic priced in the cell phone game range - e.g. $7.95 - Texas Holdem King 2, Medieval Kings Chess II and Backgammon King.
Download OTA at bb.magmic.com or bplay.com to trial them for free.
Euchre is on the way shortly and there are more to come.
The THK 2 and MKC II gaming community has been around for a couple of years so while we don't publish the number of people that are in their, it is actually quite large...