I almost never tell anyone this, but this is the most used app on my Pilot.
I think, in two years, I've played over a thousand games of it. Of
course, the version I have is called Rally, and not Mille Bournes, which is
the card game it is based on (the few folks I have told about this do not
*at all* understand my complete obsession with this game).
One more suggestion, which I've heard good things about, but have not tried
personally, is Actioneer. Almost everyone I know who has tried it, loves
it. It's one of those things that I keep meaning to get, but always forget...