We're definitely seeing the largest adoption in terms of transaction volume with Bitcoin podcasts - the main reason for this is the onboarding challenge of getting people their first sats to experience the magic of sending a Boost.

Having said that - it's definitely starting to branch out - you can check out this list we put together of top supported shows that are not Bitcoin related from earlier in the year - https://explore.fountain.fm/blog/ten-eclectic-podcasts