pngquant is a batch conversion utility to quantize and dither truecolor PNG images, especially those with a full alpha channel, down to "RGBA-palette" PNGs (i.e., PLTE + tRNS in PNG parlance). Such images are usually two to four times smaller than the full 32-bit versions, and partial transparency is preserved quite nicely. This makes pngquant especially useful both for Web sites and for PlayStation 2 development, where one of the texture formats is RGBA-palette-based (though not PNG-compressed).
DatePNG is a PHP class can be used to generate a PNG image with a given time. It opens a template image in PNG format and renders text with a time in one or more formats. The font, size, position, angle, and color of the text are configurable parameters. The resulting image is generated in the PNG format as the current script output.