For a measly US$40, you can have voice-changer software on your PC!
It's worth a listen to the demos of male-Female changes (both ways) plus added background.noise
It works with stacks of games and communications programs -
MorphVOX Pro voice changing software can be used with all online games including World of Warcraft, EVE Online, Second Life, Lord of the Rings Online, Everquest, Counter-Strike, Battlefield 2 and many more.
It also integrates with VoIP and Instant Messaging programs such as Skype, Ventrilo, TeamSpeak, Yahoo Messenger, MSN Messenger, AIM, XFire, GoogleTalk, Roger Wilco and more.
In the studio, MorphVOX Pro integrates with multimedia applications such as Sound Forge, Vegas, ACID, Audacity, IClone and much more.
And if you should happen to have a need for it -
I'm just sayin'...