Bridges (in principle at least) ferry messages back and forth between Nostr and Mastodon. That's at least, how it should work...

There are two Bridges, #mostr and #momostr. Neither work great, but Momostr is the more functional of the two. I describe it all here:

nostr:naddr1qq09g6r9wdjj6snjd9jxwetn948x2ety94tk7unt95u85et8xaaqz9thwden5te0wfjkccte9ejxzmt4wvhxjme0qgs2lys4fd8aqq5jgqcnsmm3xvas4lvhgxs8daw88z7zvqa9kkwkw8crqsqqqa28quyrhk