I think it'd be really cool if you could easily migrate your account to another node. On the registration page it might be useful to have a "Migrate Account" button which will then ask you to enter your Webfinger which then you go to the old node to give access (like you do when you login), this will then pull your information across and setup an account there. What would also be really cool if then you can set an account termination via oauth so it looks like it's a complete move.
It'd be cool if also you could point your followers at your new account (though this couldn't be it's own API endpoint as it'd be open for abuse).
This might want to be implemented as a batch process too (e.g. server could do it at times of day it knows it's low traffic or something). Also possibly a finite amount per batch of transfers (to prevent trying to take down a node via (D)DOS)
Security-wise, this is insanely complicated. I got it working with StatusNet, though.
Maybe it's easier to export (make backup) and import?
The complete account or at least the "Following" list.
Related: #670 and #679