I am using the Emic2 tts module. its pretty cool and gives you tons of options. However read the instructions very carefully. you have to send commands to the module before you send a serial statement. but the advantages far outweigh the learning curve. you can slow down, speed up, change 9 different voices and even make all statements come out in spanish. its really cool. $60 i found it at fry's but sparkfun has it too and they have code for it also.