What is Pogoshell?
First of all, Pogoshell really is only useful to people who own a Gameboy Advance and a flashcart. It uses special features of flashcarts that is not yet supported by any emulator.
Pogoshell is (at it's simplest) a replacement for the menu-program you get when you put several roms on your flash cart. But it's more than that since it actually uses a filesystem with directories so you can put roms along with other files just like you would on your computer. Pogoshell can be extended to handle different file types (like playing music, running nes and spectrum games, viewing pictures etc).
It also has an SRAM filesystem that lets you have much more than 4 saves at a time on your flashcart.
Pogoshell lets you browse and handle files in a Flash Advance Card ROM filesystem, almost like in Windows Explorer. You simply copy all files you want (both data files .txt .bmp and executable GBA roms) into a root directory on PC, sort it the way you want under subdirectories and than Flash it! I also included PogoNES plugging that will add support for .NES roms. So now to play NES ROMS on gba you just have to copy them into the PogoShell \ROOT\ folder - turn on your Flash Advance Linker and run GO.BAT All the files will be flashed to the FA Card and in your gameboy you can run *.nes files as if they were .exe files on PC