Can you implement an option where the screensaver texts (all texts including time, file details, & song title, plus anything else) are not necessarily in the same location? For example for the time, have it so there's an additional option so that time appears in random corners, or floats around the edges of the screen, or something like that. To avoid burn-in for CRT or plasma users (though mine runs on LCD so that's not a worry).
Have some sort of overlay for videos so that it displays more file info than the quick filename info that appears during the VLC Media Player playback.
Have some 3D-style transitions (like pictures that flip, or morph into 3D shapes before becoming another pic, etc.)
I'm sure I'll think of more as time goes by!
