So in the past few days we've seen three sites that have very similar meta-ideas. http://captainobvio.us/ http://captainobvio.us/ was posted recently, I've been

So in the past few days we've seen three sites that have very similar meta-ideas. http://captainobvio.us/ http://captainobvio.us/ was posted recently, I've been working on http://cluedb.com/ http://cluedb.com/ and now this one. There are also much-older ideas like http://halfbakery.com/ http://halfbakery.com/ and http://fmylife.com http://fmylife.com etc. They all have various sets of snippet posting, user rating, commenting, etc. I wonder if this is an emerging trend?