my favorite harddrive player was the archos recorder 20, except i'm sad it doesn't work with modern formats. oh well. still planning on soldering up an apple harddrive to it and sticking the guts in a classic gameboy.. the screen will be the hardest part. i wish it were possible to make the original screen work.. but probably just have to cut out a hole in the middle as neatly as possible and stick the archos screen in there; at least it's the same fugly greenish yellow, so it aesthetically fits! best part is, it uses 4xAA batteries, so that solders straight up to the game boy chassis. sound quality is bad compared to modern players, but i really don't care, i have a sansa clip for that.
speaking of which, glad to see some classic sansa fans on here. got a clip in 08 cuz it was $15 on slickdeals: i was just looking for a beater to carry on my bike, but was very impressed! there are a lot of glowing reviews for this gem and i agree with them. also got a clip+. like the microSD, prefer the old controls.
controls are key for me, since i use it in my pocket on a motorcycle. i can't have clunky firmwear or cheap buttons; the sansa delivers. i'm probably the only person who dislikes rockbox, but it's only because of the controls: when you repeatedly hit the "back" button it doesn't go to a root menu with a default position, but rather, toggles between two screens. UGH. not fun to have to pull over on the interstate just to fiddle with a menu.