The most well known that just got ported over to iOS from PC is Call of Duty - Zombie editions. The port isn't bad, but something seems to have broken and currently there are crash complaints.
http://itunes.apple.com/us/app/call-of-duty-black-ops-zombies/id471063940?mt=8
http://itunes.apple.com/us/app/call-of-duty-zombies-hd/id364159440?mt=8
Shadowgun is one that was designed from ground up for the tablet - and is really gorgeous - oh yes, plays well too. I'm not sure if it's on the Android market yet, but it was released last year on iOS.
http://itunes.apple.com/us/app/shadowgun/id440141669?mt=8
http://itunes.apple.com/us/app/call-of-duty-black-ops-zombies/id471063940?mt=8
http://itunes.apple.com/us/app/call-of-duty-zombies-hd/id364159440?mt=8
Shadowgun is one that was designed from ground up for the tablet - and is really gorgeous - oh yes, plays well too. I'm not sure if it's on the Android market yet, but it was released last year on iOS.
http://itunes.apple.com/us/app/shadowgun/id440141669?mt=8