You can share vacant seats locationally near you. And others can search the vacant seats near them using map. Vice versa.

The purpose of the app is to search seats that people takes.
Main targets are the people who commute on a train to his office during rush hour.
Especially elderly people needs seats.
And also rap top PC users need a seat for typing a keyboard.
Another targets are the people who go to restaurants at lunch time or at dinner time.
They want to know which restaurant can provide a vacant table that they take quickly.

According to above purpose, you can use the app to exchange the information of vacant seats in the trains and vacant tables in the restaurants.