I have a couple ideas for apps I'd like.
The first is not so much an app itself but a social networking template which developers could easily take advantage of. One in which a developer could finish up for any particular interest or demographic. People could find others who have the same interest and connect on a one on one basis or in groups. People who download the app for a specific interest or demographic can limit the amount of information shared. Most such apps are geared towards singles but more people than just singles want to socialise with others.
A second app is a means of reporting invasive species by location, date and extent of presence. The info would be uploaded to a webpage or database so that measures could be taken against them.