Cut down your .bum file size: change the file ending to .bmp, open with your favorite image editing software (I use Paintshop), reduce the colour depth right down to 16 colours (use error diffusion or your equivalent method for keeping it as close to the original as possible), save the file, change the file ending back to .bum. It still works fine within Poser, but it'll be about a quarter of the file size, maybe more for some files. Not as small as a .jpg, but a far more realistic size for download. I will, however, echo the call for MAT pose files rather than ready-applied bump maps.