Can't be sure about it, but you don't look like "opensource guy" material.
With that kind of attitude (no commitment, just looking for a boost in my resume) your contributions are at risk of being a waste of time both for you and for the maintainer of your target project.
Writing an obscure feature that may prove to be buggy later on and then disappear completely, not being able to help maintaining it, doesn't sound much like the kind of thing that skyrockets a resume into resume heaven.
Project comes first. Side effects, later
And sorry if I state the obvious, but you don't walk the opensource path looking for money: that's like enrolling in CS for the chicks. You'd better like the thing per se, or you'll end up feeling pretty miserable anyway.
Continuous, active contributions are those that count
Think Alan Cox, not what-was-his-name-he-kind-of-dumped-some-stuff-there-and-then-he-left.