My name is Daniel and I really liked your initiative on spreading the word about Free PDF Readers.
I'm trying to do the same for free applications for Mac OS X in my blog (http://freeapps4mac.blogspot.com/).
When I saw your list of PDF Readers for Mac I was surprised not to see Skim (http://skim-app.sourceforge.net/) witch is, on my humble opinion, the best alternative for the Mac default or the Adobe PDF reader for Mac.
Take a look at it and add it to your list, if you think it's worth it.