An ATtiny85 powered anniversary alarm, that will play one of three tones at the desired date and time.
This project is based on the work of Vishnu Aiea's Birthday-Alarm, but heavily modified to deal with the ATtiny85's limitations (i.e. No Serial port, 8 KB program memory and 512 B RAM).
The hope is that this alarm will last for a similarly long time, but without measurements of the current consumption, I do not have an estimate for how long with will last on a single CR2450 coin cell battery.