Nonono, Quon (from RahXephon) indirectly shows up in Ouran, not Toshokan Sensou.

kinda off topicI personally have trouble getting into shows that rely too much on referential gags to try to be funny. I've tried to struggle through Lucky Star many times, Hayate kind of wore me out (though I did watch the episode where they did the Gurren-Lagann parody...I'm sure you can see where my powerful interest triggers are), and I never even tried KimiAru. I tend to prefer things where you go 'hey, that's actually really clever' rather than 'hey, that looks just like this other thing from somewhere else' or 'lol he fell'.

The director of SZS, Akiyuki Shinbo, seems to have a reputation for being a little twisted when he's given the freedom to do so. (Someone here is a MoonPhase fan, he did that too) In SZS, he went wild. A lot of it hit me the wrong way, but some of the things did impress me. But as I did mention before, it was pretty uneven.

I think it's a good idea if you find a show you really like, look into the people who created it. Not just the company, though at times that can be a good indicator, but the directors, writers, designers, music composers, even the voice actors themselves. Find out what *other* stuff they've worked on, because if you liked this one aspect of this show, there's a decent chance you might find something else they've done that you would like. Or even follow them as they go on to make new things. It's one of the best ways to broaden your viewing and see something that might not get talked about much.