There are 2 options to get flash working:
1) -THIS OPTION NO LONGER AVAILABLE- Install the lightspark package. One thing to note though is that lightspark does not work with youtube.
pkgr -i lightspark
Note: lightspark has been removed from the official repository.
2) -THIS OPTION NO LONGER WORKS FOR CHROMIUM- Install the official flash plugin
Go to http://get.adobe.com/flashplayer and get tar for linux, put libflashplayer.so in /usr/lib/mozilla/plugins
Copy the usr directory into /usr if you want.
3) For Chromium, install the chromium-plugins package.