Require all email applications to prompt users whenever they attempt to send an email that includes the word 'attached' but does not actually carry an attachment.
Create a 'what did it look like then?' phone app that connects a database of vintage photos of locations to GPS in the phone.
Offer sports gamers the option of turning off commentary and replacing it with what the players and referee and managers/coaches are shouting.
Allow cellphone users who are out of battery to insert their SIM card in public payphones to call their contacts.
Create an alert sound for laptops and PCs that tells the user when their posture might cause them future health problems.