SceneMate from Tim Wiese offers tools for Unity what should come with it by default: Snap, Object painting, Align, Randomization, Object Replacement and so on. I bought this because of the Randomization and the Object Replacement functions. It costs about 10 euros, so it has a very good price, even for indies.
I have some ideas how to improve it, so I will contact the developer soon.
You can buy the asset here.
Additional info: www.scenemate.net
(It seems that the official website is not 100% compatible with Opera browser – another reason to contact him).
This asset from Unluck Software could bring additional realism to any archviz scene, I was satisfied with it.
There are different versions of the package with crows, sparrows; even with bats.
Check out in its official website!
Buy it here (Unity Asset Store)!
I also would like to post some positive reviews related to Unity asset store items and recommend it for all the users who try to avoid to spend their money on crappy stuff.
The BIG ENVIRONMENT PACK by Philipp Schmidt contains various Unity vegetation models (trees, bushes, etc.), buildings, particles, rocks, organized into multiple scenes and an to an inventory. To be honest, I decided to buy it because of the vegetation models.
I was lucky to get it in a 50% deal (daily deals, regularly discounted prices are one of the cool features of the Unity Asset Store).
The exported models from Unity could be used in Blender Game Engine, too (I made a quick test). Since I worked out a reversed pipeline from Unity to 3DS Max, it could be used even in Max.
You can find this asset in the Unity Asset Store here.