Tag suggestion

Question - didn’t anyone think of creating any help with tagging? I mean, when you add a tag, you don’t even know if there is one or not, but in order to know you need to check. But what if you make a drop-down list of tags, at the end of which a comma is added? IMHO will reduce the creation of new tags an order of magnitude (an example - which one) to post a tag for a topic that relates to Habr? habr? habrahabr? or the same thing, but with ".ru"? Or, or even write in Russian?

ps It seems to me that this will be useful especially for beginners, although it will also be useful for "veterans".