My voice over talent has always been produced through my own cartoon creations, for example I have made a rather successful series called "ComiX" even though there are only 2 episodes out, it has done incredibly well in my opinion. you can find them at diamond-armada.newgrounds.com the microphone doesn't sound too great, but I've got it all working now :P
I have done a few voice overs for newgrounds internet cartoons, and one game, but that's as far as I have gotten really. However I have had expereience with OTHER voice actors such as Michael Swain and Joshua Tomar.
My training in voice acting has always been through my own ways. Every now and then I practise different pitches, different attitudes, I watch a lot of TV to get more ideas for accents, and I basically talk all day. I mostly train myself to get a lower pitched voice by either screaming to break your voice and eventually it goes down, also I have heard even though you suck helium in it does make you sound squeeky, however in the end it actually amkes your voice deeper.. but at the same time I have been exploring different ways of speaking such as brething in whilst speaking :P
I have an Apple Macintosh G5 intel sat on my desk at the moment, which has the microphone built in it. But that's not all of what I use. I use Garageband to delete background noise and fuzz, and give the track a little less bass, and a bit of treble. occasionally I can make crowd noises by simply Duplicating the track, recording different outraged noises or happy noises or whatever type of crowd Im aiming for, and on some tracks I add a little reverb to the certaint rack to give it a feeling.
I can also make music, which is helpful because I sing as well. besides that though, I havent got many more skills to go through at this present moment, but everyday I am learning something different (I think...).