Last couple of weeks I've traveled around helping run various Day of Unity events. It's been a lot of fun, and I've gotten a chance to meet a lot of Unity game developers. Some with experience, many trying out Unity for the first time.
One of the best features of Unity is the asset store. From there you can download all sorts of assets and packages that help speed up your development.
Which brings me to a question: What Unity plugin(s) do you use?
I'm curious to know which plugins people believe are "must haves", or were useful for them in their development.