I got really choked up when I read this. I will admit that I have not seen any of her actual films, but her work as a voiceover artist was so great and she had so much potential.
Luanne, who she voiced for 13 years in King of the Hill, was my favourite character in that series (and I just happened to watch Baby Manger Einstein the other day, which already had me sad because it's the last Luanne-centric episode of the series). She was also Colleen in Futurama: The Beast With A Billion Backs - easily one of the better 'one time' characters of the series - so it's going to be kind of bittersweet next time I watch that (which is often as it's my favourite of the four Futurama features).
Totally bummed out right now. RIP.