Bilingualism and musical proficiency has been correlated with increased cognitive abilities. http://en.wikipedia.org/wiki/Cognitive_advantages_of_bilingualism http://en.wikipedia.org/wiki/Cognitive_neuroscience_of_music#Musician_vs._non-musician_processing
I already know a second language, and dabbled in piano during childhood but never got past reading musical notes (I just memorized songs key by key and played them).
My question is, would investing say, an hour everyday towards these efforts be worth the cognitive gains? Or would I be better offer spending the hour concentrating on matters that are actually relevant to my field of interest? I theorize the cognitive gains - increased processing speed, increased verbal memory - would then create a "better engine" for working on daily tasks, thus increasing overall productivity in a way that is proportional to the cognitive benefits.
Of course, there lies the problem of uncertainty - would I cognitively benefit at all, given that I already have exposure to a second language/instrument?
I would enjoy learning a new language (say German) or relearning piano, but I don't see how it could be at all applicable for a student intended to take on a software engineering job after graduation.