These are small softwares that I made. Use them at your own risk.
I have only Sharp IS01, IS03, ASUS ME173X, and Zenfone 5. So I don't know whether they work on other android phones and tablets.
Source codes are also available.
If you don't know what dingux is, you don't need to read here:-)
A two-column style file manager. You can Copy, Move, Delete, Rename files, and Create Directory on dingux.
A simple text file viewer. It can display Japanese, and if you put an appropriate UTF-8 font file, it may display various languages, I think.
A Game Boy emulator "gambatte", compiled for dingux. I modified it a little to use on A320: fitting to a QVGA size screen, simplification of a sound filter.