Mobile Phone “Turn-Based” Online Chess

I’m looking for ways to play “turn-based” correspondence-style chess that I can play from my iPhone.  My idea is to play a slow-paced game with friends, making moves at my convenience during “dead time” such as waiting in line.  The ones I have found are the following:

1. Chess with Friends
Advantages: Very easy to use iPhone app with push notification when your turn to move
Disadvantages: Only two iPhone users can play, no web interface

Advantages: Can play on phone or web, other apps and mobile interface available for other smartphone users
Disadvantages: Limited number of moves per day with the free membership

Advantages: Low-bandwidth web interface, other games available to play
Disadvantages: Other phones not supported, no iPhone “push” notifications (big downside – have to open the app every time to see if it’s your turn to play)

I’ve been leaning towards “Chess with Friends” to play with iPhone users and with everyone else. Anybody out there know any others?