Mastodon supports WebFinger to find a Mastodon account by searching for an email address. This is helpful if you’re looking for someone but you don’t know what server they’re in.
After a year and half since joining Mastodon, I have made social.coop my place in the fediverse. You can follow me there at email@example.com. I’m happy to be part of a server funded and governed by its members.