Shows Mr. Jingles when you caught up on all notifications.
Update: Unfortunately Google has decided to get rid of the notifications all together, rendering this extension useless. It is no longer listed publicly in the chrome web store.
Mr. Jingles was a beloved (by some) Google notification icon informing you that you had caught up with all your notifications. It even wiggled a bit, happy that you cleared your list. Although it still exists for Google+ notifications, it has disappeared from most other services (GMail, Maps, Photos, ...).
This extension simply inserts Mr. Jingles back into Google notifications, wiggling and everything. Ready to brighten up your day.