I was reading this post by Andrew Watt, after finding it on Daring Fireball.
Andrew Watt mentions that he can't force the entire web to change their stylesheets to make certain characters appear correctly. He resorted to changing the entire font which was causing the issue.
I think I have a mostly complete solution, however. A simple stylesheet included in Safari's preferences should be able to solve the problem. Here is the stylesheet I came up with and tested on his demo:
body * {font-family: "Myriad Pro", "Helvetica", "Hiragino Kaku Gothic Pro", "Osaka", "Zapf Dingbats" !important;}
Note that this is not as complete of a solution as Andrew's, as a few situations could probably cause the "!important" to be ignored. Even so, it has the benefit of allowing me to change most of the internet to use Myriad Pro, my favorite font.