I've sen that one, actually. From a literary standpoint, I think their 'special powers' were more along the lines of some kind of play at Haruhi's fate or destiny. The only one who stood out very much was Mikuru as she was from the past, though, there's an overlying hint she may just be reincarnated. Anyway, I've participated in a few of those types of threads and in my experience you need one of two things to be successful: lots of players (lacking in that area), or a solid plot.

But if you want Sci-Fi, I just posed a thread based off Mass Effect. I haven't posted any details on the story because I'm waiting to see who all would be interested. Mass Effect is an incredibly compelling story, despite the few parallels it has with Star Wars (Mass Effect is better in my opinion). Please, if you're interested in a Sci-Fi thread, give mine a shot. You don't have to have knowledge of the game to join. I can explain anything that needs explaining.

View it here.