Any P2P file sharing program can perform this.
Like Bit Torrent Sync for example. With LAN you should be able to share files and see other presets.
I'm not sure if this belongs in the Game Discussion folder, but yup, seeing everyone's preset would be fun.
I'd like to see this happen, especially since I can't download any presets, and I would love to see some of the creations that other people have come up with. However, I can't even imagine the slowness that would occur. Of all the presets in the world...trying to load at the same time...it just seems too good to be true.
That's why I make all my characters so that everyone can see them. :(