How to externally load assets into Unity projects for android

is there any way I can create like a package file that co-exist with my actual unity project on android? so that I can load stuff into project from this external package file?

Asset Bundles seem like the most obvious answer. They are a pro-only feature, though.

http://unity3d.com/support/documentation/Manual/Loading%20Resources%20at%20Runtime.html

note: created asset bundles would be in a folder "StreamingAssets" inside of your "Assets" folder in order to compile them correctly.

Hope that helps.

==