Soo, in order to get all bunnies, you need to post in your journal. This even is pretty interesting and most of the bunnies you'll get by just doing what ever you do in the Gaia normally. But here's the list I've got from the Easter event forums. whee

This is how you get 41 bunnies and the bunny item:

Interactive Gaia Blue: 7
1. Log into Gaia Online.
2. Visit the Gaia Blog.
3. Visit the Gaia Labs, and activate/deactivate a feature.
4. Visit the Gaia Cash.
5. Visit the Offline Events/Convention.
6. Visit the Storyline Manga.
7. View the latest Developer Notice (Check the homepage, scroll down).

Angry Red: 7
8. Visit the My Gaia.
9. Change your Status
10. Create a new Journal Entry.
11. Edit your Profile (must rearrange boxes or add/delete).
12. Vote in a Easter 2011 forum Poll (records abit later).
13. Quote someone in the Easter 2011 forum.
14. Create a new Private Message to someone.

Lovely Orange: 4
15. <3 a thread in the Easter 2011 forum.
16. Send a Friend's Request to someone (does not need to be accepted).
17. Receive a Gift.
18. Save an Outfit in your Closet.

Sparkling Gold: 5
19. Visit the Shops.
20. Tip a post.
21. Buy an item from the Marketplace.
22. Sell an item onto the Marketplace (does not need to be sold).
23. Bid on an item in the Marketplace.

Social Grey: 13
24. Visit the Rally.
25. Visit the Slots.
26. Visit the Electric Love Faktori.
27. Visit the Fishing.
28. Visit the Word Bump.
29. Visit the Blackjacks.
30. Visit the Tiles.
31. Visit the Towns.
32. Visit the Pinball.
33. Visit the Jigsaw.
34. Visit the OMGPOP (Choose a game).
35. Visit the MStyleLab.
36. Visit the Earth Day Forest Stage.

Naruto Swirl: 1
37. Visit the Dumpster Dive.

Facebook Blue: 1
38. Visit the Anime Player (you must let the page load for a few minutes).

Diedrich & Easter Bunny: 1
39. Say Bunny or Easter in a post (Easter 2011 forum only).

Invisible: 2
40. Change your avatar and save it
41. Get quoted by someone.

Edit: Changed the list to a bit better working one. Tested with a mule so it's a fully working list. 3nodding