PNG's are very useful if you use them for what they are intended for. That being vector-based graphics. For most uses, the raster-based (bitmapped) compression methods are more useful, but if you want graphics that are truely scaleable, and with editable elements PNG is the way to go. I use PNG for my "library" images in Fireworks, then export to gid or jpg as appropriate to use on the final page. IMO, PNG is a much better replacement for GIF's (incidently, the patent expired a few days ago), but not all browsers support them correctly. PNG is a poor substitute for JPG, period.