It's not too much of a secret. I love Star Wars, Harry Potter, Xena, The Last Airbender, Torchwood, etc.. My 3yo son has already been instructed that when he's old enough to buy me Mother's Day gifts, no jewelry or flowers for me. Buy me Star Wars action figures! I'm making our costumes for Halloween this year - we'll be Dora and Diego - and I realized I'm basically cosplaying them. *facepalm* I can't wait until he's old enough to get into The Last Airbender, because I want to be Toph, and he'd make a cute Aang. I'll even shave his head! I made a Lando Calrissian outfit for him for his first Halloween. He looked awesome.
Also, I read lots of fanfiction. Used to write it, but haven't ever since the "padawan" came along. Hopefully someday I will again. I even discovered that there's Wiggles fanfiction out there. I'm sure there's also Dora and Diego, but I'm not interested in reading it.
When all of my Star Wars friends became parents, our big discussion was at what age and in what order to show the movies to our kids. This was like THE most important parenting decision we would make!