I would be up for this! Since I know Ruby hopefully it wouldn’t be too hard getting familiar with Crystal too.
One thing I always thought might be good is using it for Elixir/Erlang nifs, but I think @OvermindDL1 said this may not be a good fit.
Other than that, would it be good to use for things like graphical work? Do you know what the Crystal core team are targeting it at?
(Speaking of the core team, I think I spoke to one or two of them via Twitter a few years ago and they always came across as very nice and very much in the spirit of Ruby… which is always a huge plus 
)