[anoved]

Nobody's useless. It's easy to get wrapped up in the impression that we are defined by our jobs (especially around this site), but we aren't. I have had some unrewarding jobs myself, with little big-picture purpose and no easy way out, but the solution is to find (and make) value in other activities. Cultivate a hobby or an art or a programming side project that is important to you. Even the small "feel good" activities you mention are not insignificant if they impact someone else - and if you choose activities that are more interesting to you I suspect you will find them to be more satisfying.