I meant to post this months ago (I made this shortly before Halloween of 2009) and forgot about it. And now I'm a bit embarrassed to post it because it is so wrinkly and worn out now. Oh well...I guess it shows how much it my son loves it.
A friend helped me make this reversible cape: Batman on one side, Superman on the other. Once again, I didn't think to do tutorial pictures while I was making it (I really need to work on that), but thankfully, someone else has already done that (I just found it online...horray!).
Check out the tutorial here. Now before you get started, let me just tell you that I opted not to use felt (because it balls up and doesn't look as nice sometimes after you wash it) and used cotton instead. I also was using scraps, so I had to piece the neck straps on, but in the end, I was happier with that option. Now, there is more strap length inside the seam, so I can just open it up and adjust it as my son grows. I didn't use velcro on the straps either...we just tie them and that works for us.
Good luck! If you have any questions, I will do my best to answer them.