I've got a fair bit of free time for the next few months and I'd like to try learn something useful. For example, I've noticed some jobs and volunteer opportunities being posted in EA circles for web developers. It seems like one could potentially gain a usable understanding of web dev in about 6 months (although I may be very wrong about this). I'd welcome any suggestions, whether the skills are technical or more 'soft'.
I'm interested in answering a specific question so my answer's at least useful for a specific real (or hypothetical) person, rather than provide generically worded advice that ends up being useful to nobody. :P