Not really a niche language. Fantastic web server development. A more flexible and powerful language than python—the metaprogramming can be ridiculously powerful (when done well)—without the nonsense of white space sensitivity. ActiveRecord is perhaps the best ORM out there. Rails has tons of functionality to get running.

Overall, a pleasant and expressive language with an incredible community. Python ends up "winning" because of pytorch + pandas, but is (imo) a worse language to work in + with.