Info for new users:
If you've registered and haven't received your activation email, check your spam folder for it, particularly if you're a gmail user. If you could mark it "not spam" when you do, that would help too.
If you registered before today (Aug 27th 2014), you almost certainly won't have received one anyway. Give TSB a shout on twitter and it'll get resent [eventually].
Likewise if you've registered since this post but don't find anything in your spam folder either.