We just launched and we already have three:
Civi is wide enough that these need not be duplicates, as it also handles snail mail and non-civimail mailing. This however is not so obvious, user friendly, when you're choosing tags. Do we start consolidating, just expand the tag wikis or something else?
Mail and email are obviously synonyms. However, there may be a useful distinction between CiviMail and base-level email configuration. Someone having outbound email trouble leading to no receipts going out isn't necessarily going to be looking to a CiviMail tag, especially if they think "I don't use CiviMail; I use MailChimp".
Once you have 1250 reputation, you can define tag synonyms.
