Earlier this month I made a GUI to build ROMs with Goomba Paletted. The motivation for this project was to allow borders with a shape other than 160x144 or "none," which was accomplished by editing the code of the Append program that comes with the emulator and including it in this software. I also added several other features to test my skills, including using and previewing palettes (.pal or .txt).
Download/more information: http://www.lakora.us/java/jgoombabuilder
Here's a video showing Super Mario Land in action, with my custom borders and palettes:
Download/more information: http://www.lakora.us/java/jgoombabuilder
Here's a video showing Super Mario Land in action, with my custom borders and palettes: