Lanyard fitting for the iphone?

im about to purchase a 32gb iphone 3gs for my birthday and i really require a lanyard fitting (either on the phone itself or via a case) so i can hang it around my neck so i can use it (im in a wheelchair with limited arm movement).

Can anyone recommend a case which allows a lanyard but also allows the phone to be used without having to remove it or open the case to use it?

Thanks in advance.

Gaz