Bajdi has made a simple MP3 alarm clock out of an Arduino Mega2560. It features a 128×64 graphical LCD display, a couple of buttons to set the alarm, a realtime clock and an MP3 module and speaker.
It’s a nice little project that does what it says on the tin. It uses an SD card to store the MP3 files (at 96kbs). It’s a nice example of what can be done audio-wise without the new Arduino Due’s DACs. You can read more on Bajdi’s blog.