Rainmaking is a superstitious belief that performing a dance will make rain come. I guess it's somewhat analogous to the term snake oil salesman but, whereas snake oil salesman sell their bill of goods for their own gain, rainmakers, it seems to me, are acting more as community placebo's, calming people's nerves.
I'd like to tell someone that "I'm a software developer - not a rainmaker" but I feel like that's a little too obscure. Is there an analogous reference I can make that might be more broadly understood?