The SparkFun VoiceBox Shield adds all the capabilities of the SpeakJet voice and sound synthesizer to your Arduino Project via serial commands.
Here's the official Arduino Ethernet Shield With PoE Module
This Arduino shield interfaces the Pololu Wixel wireless modules to your Arduino-compatible project, enabling simple wireless programming, debugging, and control using standard Arduino software.
This Arduino shield rocks a socket for wireless modules, such as Digi Xbee, so that you can float your bits and bytes of data through air with the greatest of ease.
This proto shield comes with a socket for wireless modules, such as the Digi XBee, and a built in regulator and a big ol' prototyping area.