I've been looking into that lately myself.
Card wise check out Shadow Era and Cabals for free.
Necronomicon Redux or Assassins Creed Recollections for 99 cents each.
Here's a monster list of what I've come across.
Too lazy to link everything now...
- - - - -
List of top board games . . . Most all these appear to be quality.
Just depends what you are looking for:
(these and more found here:
http://ipadboardgames.org/author/keith/)
Tigris and Euphrates
Carcassonne
Ticket to Ride
Forbidden Island
Caylus
Neuroshima Hex
Small World
Catan HD
Puerto Rico
Ascension
Elder Sign: Omens
Cabals: the Card Game
Ghost Stories
CubeSieger
New World Colony
Titan
Samurai
Bang!
Tikal
Battleline
War of the Roses
Keltis Oracle
Medici
Ra
List of card-based . . . some overlap
(
http://forums.toucharcade.com/showthread.php?t=100265)
Sword & Poker
Sword & Poker 2
DeckMake Fantasy
Shadow Era
Ascension: Chronicle of the Godslayer
Urban Rivals
Kard Combat
Orions: Legend of Wizards
Orions 2
Necronomicon
Arena 9
Fantasy Adventures
Heroes Blade
Infinite Battles
Pagans TCG
Riese: Battle for Eleysia
Stack & Deploy
BattleSpell
Urban Rivals
Soul Card Master
Dungeon Solitaire
Summoners
Battle of Gundabad
Moonga
Samurai Blooshow