Not for your mobile phone, but great for use at home and printing to take with you:
My ToDo List
application was designed to be very simple, and the simplicity of it makes it quite powerful for use in making shopping lists.
Enter all the things you need to buy on the ToDo side and print it. You'll get a sheet with little boxes to check off.
When you get home, move all the items you did buy to the Done side.
Next time you need to go shopping, you will not only have the list of things you didn't buy waiting on the ToDo side, but the Done side has all the stuff you have previously purchased, ready to select and move back to the ToDo side and buy again.
You have no idea how great this is to prevent you from forgetting to add things to your list. It kind of does half the thinking for you.
You can keep a separate list for every different type of shopping you need to do: one list for groceries, another for office supplies, one for your kid's school supplies, another for a party or specific project.
Lists are stored as 2 separate plain text files, one for ToDo and other for Done. Since they are plain text, you can copy either of them and change the file extension to .txt and do the same things with them as any other plain text file, including storing a copy on your mobile device or emailing it to someone that doesn't have a copy of the software.