Sorry, duplicate topics. Please see this topic for more information:
http://forum.unity3d.com/threads/202280-UnityPackage-TOOL-Released!
hi misthema,
I would like to thank you for your asset manager ! This is really helpful and impressive 
I’m currently working on a tool able to manage and search all your packages and retrive asset store infos quickly. I can send you the beta if you PM me (seems that you locked the PM).
I didn’t actually knew that we could read and unserialize the rest of the file and I would like to ask you if you could help me achieving this as well on this project or if you prefer keep the magic
This feature is really missing in my tool and it would be really interesting to work on this.
Looking forward to your response
Anthony
Hi Anthony,
Thank you for your kind words! Looks like PM features are put as ‘off’ in default. I will PM you soon.
There’s no information - at all! - about Unity Packages in the internet, so I had to do some “digging”…
I was actually going to add the feature to manage your packages… Not sure about Asset Store stuff tho.
PM you soon! Thanks again!
~misthema
EDIT: Forgot to mention, that the code I’m using to open packages is open source and can be found here: GitHub - bradgearon/unity-3d-package-extract: Simple method to extract .unitypackage files, since it seems to blow up unity on occasion and if you have lots of assets there is a good chance you just want to pull in what you need...
See the first post for UPDATE info and new DOWNLOAD link! 
Have fun!
Sincerely,
~misthema