I think it depends a lot on what you want to do.

If you want to get hired by a top company (Google and the like) I guess you should do non-trivial open source contributions to make an impression

If you just want to do contracting you don't normally need a lot of code-exhibits - you need to be able to sell yourself in an interview situation and then communication skills are just as important as technical skills (but the people that interview you probably are more desperate to find someone then you are finding a project).