...Random Bytes...

Going on what I've seen around the internet that duplicate Arial fonts could cause the Nik plugins to crash I opened up 'font book' and took care of the dups. That still didn't fix the problem. 

Then going on the assumption that the Arial font was still the issue I started looking at the versions of Arial on my computer. All Arial files seemed kind of old. Using an application called Pacifist I looked at the Snow Leopard installer package. Doing a search for Arial I found that the version numbers were different. 

Using Pacifist I copied the newer versions of the Arial font to my computer and removed the older versions. There are a few places were fonts live on your Mac. Make sure you find out where your current version of Arial lives, remove and replace with the one from the SL installer.

My Nik plugins now work. 

(UPDATE: An alternative fix: Your Snow Leopard install may of installed the updated Arial font with out removing the old outdated Arial font. When you use Font Book check within the Arial listing to see if some styles (regular, bold, italic, etc.) are duplicate. Select one of the dups and press "command i" for info. You want to keep the current fonts and styles (version 5.00) and remove the old.)