Ok, I think this is one of those so-simple-it's-cool sort of things. It's a smartphone app for managing your grocery list, and the best part is it's shareable among other family members with smartphones.
So for example, my wife is sitting at the dentist's office and remembers that we're out of bananas. Rather than have to remember to add it to the list when she gets home, she pulls up this app on her phone and types in "bananas." I'm at the grocery store and I see "bananas" show up on my list in real time.
You can share your lists with whoever you like. And if they don't have a smartphone, it's also possible to update the grocery list online from a PC.
Slick, eh?... and Free!
(Disclaimer: I have no affiliation whatsoever with this company. I just thought I would share because it's neat)