One thing you might consider is putting together a workshop (say about 3 hours) for your coworkers. Get management to sign-off on the idea so it is an official workshop.

Spend a good deal of up front time going over basic coding practice and style (consistent indentation, strict, warnings, checking return values) then move into more specific areas. Compile up a list of example code (or pseudo example code) from problems you've helped with in the past --- so the examples are targetted at the kind of things they are actually doing --- show the problem code (no names), and your version, and most importantly, why and how your version is an improvement.

You may even be able to coax management that a once a month afternoon programming workshop is a good idea. These wouldn't necessarily be be in a presentation format as the above, but more open discussion of current projects and troubleshooting code (but always be prepared with your own examples of code that needs improvement, kind of along the lines of MJD's 'red flags and repair' articles on perl.com --- you'll need these if no one brings any code of their own, or perhaps just to get the ball rolling). Such a monthly workshop gives both your coworkers and yourself a good chance to keep learning and improving, and can certainly improve productivity (that may help you sell it to management). If management won't bite, see if your coworkers are interested in informal (voluntary) version of the same. If they aren't interested in putting in some time and effort in self improvement, you needn't feel compelled to keep helping them now (imho).