That's fair about Go. The last 3 were a bit random, I was just trying to get a bit more variety in there beyond the more mainstream stuff. I realise that Go isn't really used by anyone, but it has had a bit of airtime simply due to it being a Google tech (not to mention the authors). I guess I mean hottest in the sense of most interesting to people.
Yeah, good point. Personally I use Redis so I am tempted to add it just because I'll have something to say about it. Although my gut tells me that Mongo might be the 'hot' technology---seems to be popping up a lot of late.