Here is a nice new shield for the Arduino. This Audio Shield allows you to record and playback audio using the popular Winbond ISD4003 chip. One thing that looks like it was a bit of a pain was having the 3 volt Windbond chip to interface to the 5 volt Arduino.
Windbond ISD4003 datasheet (PDF).
"The Voice Shield™ (VS) is an analog audio shield for the Arduino that allows you to play audio sound bytes. It could be used in many different Arduino projects, such as; a talking clock, DIY Arduino talking GPS, robots, alarms, motion based sound effects etc …"