I found an interesting site that hosts free mobile versions of various magazines, designed to be viewed on a phone or PDA. It's called Perooz.
Admittedly, most of the current magazines are effectively soft porn, like GQ, Maxim and FHM, but there's also Stuff, which showcases gadgets, and some comics.
The format is interesting. They break the magazine up into a heap of JPEG images. There are different versions for various devices that have different screen sizes. For my Treo 680, the Zune versions seem to work well.
They also provide a few short MPEG 4 videos, including movie trailers and music clips.
Hopefully, they'll add some more interesting titles over time.