Hello Fellows, I want to have some true friends. Please give me some, will you?
It doesn't work like that, in real life. And by the same token, we can't just point you to a project, without knowing more about what you want to do, what you can do, what you want to learn, and how much time you want to invest.
Do you want to do something with math? cryptography? web stuff? databases? classical "scripting"? graphics? GUIs? calendar stuff? spreadsheets? word processing?
Spending your free time on a project only works out if you really care for that project, so we can't just throw something at you, and expect you to be happy with it.