Robin Good has a nice guide to using YouTube to promote your organization. His suggestions:

1. Create and customize your own channel.
2. Choose your niche.
3. Create short form viral content.
4. Tag and categorize.
5. Create niche-targeted playlists
6. Promote your video with YouTube email and bulletins.
7. Leave video responses.
8. Join or create YouTube groups.
9. Chat in the streams
10. Use active sharing.

As always, he has good examples, clear instructions and additional resources. Even if you're not currently using YouTube, it might be worth a visit to see if maybe you should get it on your radar screen.