Antares Audio Technologies has announced Voice Thing! (Windows XP/Vista; $34.95), a new thing to change your voice with. It allows you to process your voice in real-time and use your altered state in various ways, such as for online gaming, voice chat, and video and Podcast production.
Voice Thing! requires a microphone and a PC application that accepts audio input. Once you've recorded your voice into the computer, you can pitch-shift it, change the quality or gender, translate it to the sound of another creature or animal's voice, simulate different environments for it, and more.
Try a time-limited demo version at the Voice Thing! Web site.