Mat has ported the image viewer zgv on Gp2x.
Features: File selector with thumbnails (optional).
Easy prev/next images navigation.
Zoom In/Out. Only display at 320*240 or original image size.
Rotation.
Multiples image formats: JPEG, PNG, PBM/PGM/PPM, TIFF, BMP, TGA, PCX, mrf, XBM and XPM...