I was thinking about this question: Merge of tags `info-visualisation` and `info-visualization` into ìnfoviz`
And I was also looking around and saw several other tags that should be combined - "dropdown" and "drop-down-lists" stand out right now to me.
As it stands, there are only 7 users on the site that can create (and I'm assuming vote on) tag synonyms. And Patrick is the only one of those that seems to know about them, since he's the one that has created any (and none got voted up so far). I think this could be hurting the quality of content on the site by making it harder to identify duplicate content as it comes in.
To me, it makes sense to make this function a little easier to accomplish, at least the voting portion of it. Waiting for four additional people to vote up a synonym when only six other people on the site in total can do so is not really a working situation.