At work, I was part of a team that developed computer-aided instruction materials for elementary-level students. Along with conceptualizing the characters for the project, I provided the voiceovers for each of the main characters and supporting characters. I used voice-editing software for the female characters, but not for the males.
I grew up in the 80's. As such, I was exposed to cartoons like the Transformers, GI Joe, He-man, Thundercats and many more. These shows had many memorable characters and voices, which I proceeded to imitate. Since then, whenever I get to watch a good cartoon or animated film, or hear an interesting voice, I try to imitate it and see if I can add it to the list of voices in my head.
I can also draw and animate using Macromedia Flash.