Well in my opinion you should create something that helps yourself (!) - not others. Think of your all day life - some things you do pretty often and try to find a project, that really would help you. If there already is a great open source project for your purpose (and probably there is), you could try to get part of it... improve things... read code (which is a good way to get a better skillset!).
Targeting a better skillset or developing just for making money most of the time does not result in good ideas or products - but a project of personal interest will motivate you for a long time.
Personally, i created software, that i always wanted to have, but did not find something, that fitted all my needs - and it is still fun to work on it... e.g.:
- A simple tool to transfer files
- A tool to improve scanned document images and create a pdf
- A tool to convert audio files