GBA Jpeg Viewer by Tony Savon allows you to generate a rom including a slideshow using your windows PC. The changes for this version:

Version 2.3* Added a color dithering system: greatly enhanches display quality* In thumbnail mode more infos on the pictures are shown* Added pause option in slideshow mode* New Graphics for menus* In Jpeg Packer added settings for brightness and contrast* Slighlty faster jpeg packing