I've been collecting spawn eggs recently for the hell of it, it's nice but useless, like a stamp collection. I think that it would be cool if there was a forum medal, similar to the treasure collector medals where if you have all the types of spawn eggs you are awarded a medal. These eggs are currently obtainable by voting or winning a lucky lotto, and sometimes in other rare server events. The eggs could be made to be obtainable from the star shop so that it's easier, but still difficult to obtain these eggs. Doing this would not only add a medal to the forums, but also help create a market for spawn eggs as currently they aren't really bought or sold (other than eggs such as pig and sheep) due to their uselessness.
How about if you collect 5 of one type of hostile mob egg (so not the eggs you get from voting) you get a medal that shows whatever mob egg you collected 5 of. There could be a golden mob egg for if you collect a certain amount of every mob (not hostile) perhaps? Such as, if you collected 1 of every single mob egg (and there are quite a few), but them in a chest, and applied for a golden mob egg medal.
You have the easter egg lore eggs? +1 for this suggestion though, but if this happens, I don't see why the music disc medal can't be made either for a complete music disc set
The admins would have to take the eggs from you permanently to make this work though, and I'm not sure if everyone is taking that in mind, because otherwise it'd be a "Hey, can I borrow your collection to get the medal?" festival all over the place.