maaalin,
I suggest the best way to share themes is to create a TEMPLATE. That way, people can modify it to their liking. Remember that there are players with 1.2" and 1.5" and 1.8" screens. Not to mention the various menu items as well - some have games, some don't. So you can't just make 'one' theme and expect it to work on all players given the different screen sizes and main menu items.
I created a startup and shutdown screen for the 1.5" screen players here:
http://www.mympxplayer.com/viewtopic.php?t=10. It has the Photoshop file too so people can modify it to have their own menu items.
I would recommend to anything making a theme to try to include a photoshop file or original source template so that people can change it to match the items on their menu. But then again, u are also left with differing screen sizes too....