I created an app that allows you to upload a pdf and it returns a copy of your PDF with the page order reversed. It's available here: http://reversepdf.appspot.com/
Initially when I googled how to do this in Adobe Acrobat, the first few results had fairly complicated solutions. After I made the app, I ended up finding an easier way to do it in Adobe (in the 6th from the top Google result on "reverse pdf order acrobat"...):
Oh well, it was a fun project.