Plex for Android is a great program that allows you to use Plex on your phone, without any server. This is not the most extensive software package out there, but it does have many useful features such as the ability to sync your music and videos across multiple devices. I have used this program for a while now and love it. There are many more options available if you need more functionality. You can also use the Plex web interface, which does allow some basic customization of the software.
The only problem I have found with the free version is that the apps themselves don't always update very often or at all. Other than that the program works perfectly on the android phone. It is available for free in many places on the internet including the play store, Google play store, and Amazon app store. The free version lacks some key features such as video support and push email. There are also many other paid versions available.
If you are looking for a free, open source solution to organize your media files, this software is it. There are many positive aspects to using this software, including the fact that you can sync your files across multiple devices. There are several other options if you want more functionality. When downloading the software make sure you read the terms and conditions to make sure you have all the features you need. I enjoy using Plex for android and have had no problems getting everything installed and working.