Perhaps it would be better to submit https://joinmastodon.org instead of the flagship instance. The project homepage has links to all the info as well as a directory of servers (instances), which might spread out new users better.
Of all the random strangers hosting the service, I waited until I could get onto the instance hosted by the actual project itself; the bus factor feels higher, and the account suspension process less arbitrary.
https://web.archive.org/web/20170406103653/https://mastodon.... (April 2017)
Due to exceptionally high traffic, registrations on this instance are closed until quality of service can be assured for existing users. Choose one of the various other public instances to sign up!
https://web.archive.org/web/20170806214711/https://mastodon.... (August 2017)
Given that this is most shared instance, to preserve the ideals of decentralization we have closed sign ups in favour of spreading new users through the various alternative instances — you get the same network wherever you sign up. Click below to find one:
A few months later, I think mastodon.social has been fairly open to signups, especially now that we've got all these French and Japanese instances up and running.
Throw in a DHT and a key pair for every user and you could fully divorce account ID from instance.