For what it's worth Jeff, I really like more days that are more specific as opposed to a single day. It is difficult to express and adequately emphasize exactly how starved for feedback many developers who donate their works are and how under appreciated many feel. And often more results come from more specific requests so "review a plugin today" (I think) will generate more activity than "somehow do something nice for a plugin dev".

I think keeping the request simple and to the point is beneficial and encouraging people to do more, more often also has a great impact. And when you think about it, there's really lots of great WP holidays you could push for. Stuff like:
- Review a plugin day
- Review a theme day
- Donate to a plugin author day
- Donate to a theme author day
- Tweet your favorite WP blog day
- Blog about your favorite plugin day
- Rate a WordPress.tv video day
- Help out on the forums day
- Beta test something day
- Thank your local meetup organizers day
- Review a podcast day
- Thank your hosting provider day
- Get involved day
- Troll Jeffr0 day...
Ok, maybe some are ridiculous but still. I think we are all in this together in a way and encouraging everyone to show appreciation as often as possible seems a nice idea to me.