Extending user reference I have built a content type named "Project" which will showcase some projects by the members of a group. I have used a user reference field in that content type, so that the contributors of a project can be enlisted.

Now I am trying to put in the user's profile page the links to the projects he contributed to. How can I achieve that?
You will need to use views and panels. You will create a new user home page using panels. Within that panel you will want to create a view that lists all the content types Project filtering on the user.

Otherwise, you will need to create your own module.