I really wish I could comment on things like "So and So Finished Learning Such and Such" when they show up on the homepage (or in the profiles for my friends). It'd be great to post inspirational or supporting messages like "great job!" to learning Mining or "isn't it great?!" for the highest level of Animal Kindness or even "omg can I come visit?! lets have a housewarming party!" when a friend finally gets a house