orb (link) is a handy tool that aggregates various online, non-terrestrial radio stations on a single site.
Data is pulled from public APIs exposed by the various broadcasting softwares that these stations use. As a result, orb only uses radio stations where current stream information could be easily accessed.
So far the implementation is pretty minimal but someday I'd like to set up notifications so that you can save your favourite shows and be alerted to when they are being broadcasted.