Omnomnom Lite is a snake-grows-as-it-eats-apples game with plenty of options. You can adjust the settings to make hitting walls deadly or not, play at three levels of difficulty, play in three playing field sizes (including a progressive size field that starts out small and grows larger as you play) and you can choose between two visual skins. The snake controls fine with taps to a virtual D-pad, but the game inexplicably switches to a different D-pad-like control in landscape mode -- it's awkward and confusing. The lite version of the game offers only a few levels of apple eating.
Links:
[1] http://www.maclife.com/user/adam_berenstain
[2] http://www.maclife.com/article/iphone/omnomnom_lite
[3] http://www.maclife.com/article/iphone/tiltsnake
[4] http://www.maclife.com/article/reviews/pacman_and_ms_pacman
[5] http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=290232086&mt=8
[6] http://phase2games.com/support.php