I'd love one! We're all Android in my household, so an iOS app wouldn't do us any good, but an Android one would be great.
Besides showing the equivalent of the mobile version of the web page, some things that would be nice (but not necessary, per se):
1. Easy way to add item images using the device's camera
2. Easy way to add new items via scanning the barcode ("UPC"/UCC-12/whatever)
3. Easy way to check items as received via scanning the barcode
But really, just having an easier way of getting to the list itself would be great -- a good start, if nothing else. :)
K.