They aren't important at all really. I mean, maybe the Ianto/Jack stuff in the third one is a nice reference but it's not IMPORTANT, if you know what I mean. If it's that or CoE, I'd watch CoE FOR SURE. Or listen to the Dead Line and then CoE. But really, just CoE!!!

And for the meme: TORCHWOOD!!! Cause it's all I'm thinking about!