I just got my lastest Servo Magazine (electronic subscription) and I saw a new speech chip for a nice rethro style robot voice. This new chip, RoboVoice, is like a brother to the SpeakJet, but with a built in text to phonemes converter (800 rules database). It costs $24.99 but for the Servo readers there is a discount for the month of November so you can get it at $16.99 from SpeechChips.com: http://www.speechchips.com/shop/item.aspx?itemid=22
The chip is a PIC running at 16MHz with a built in DAC (no external filter required) and 16MHz clock so there is no need for an external crystal so you just need to add a few resistors and caps and of course a small amplifier, just like you would do with a SpeakJet chip. To connect it to the microcontroller of your choice, you need a Ground, a Serial Out and a Bussy signal. You may opt out for the Bussy signal that gets High when the chip is speaking so you know not to send more text until it is done (you can use this pin for a LED). The chip is 3.3V but 5V input tolerant, still you may want to add a resistor divider at the serial input pin just to be safe. All this and more is covered in the Servo magazine. If you can't afford the magazine and want to read the article, I can give you a copy of the article, just let me know. They cover the schematic and the code for Basic Stamp 2, Picaxe, Arduino Uno. Also, the link to the webstore has some videos that demonstrate the chip functionality.