WOW, 233 pages of what people would do with their EVO.. LOL. I"ll add mine in as well.
With all things considered in my life right now, it would freakin' awesome to use the internet while on a call. Especially since I'll be having my first kid shortly. This opens up all kinds of possibilities to access information quickly. For instance turn by turn directions to the closest hospital while calling my family and telling them the baby is coming. No no no, I have route planned out for that but you get the idea. LOL.
I could be talking to my wife, a family member, or a friend while using apps that require internet (like ShopSavvy) to find if there are items better priced elsewhere. I seem to always find myself in a situation where I need to look something up while on a call. I just don't know how that always happens to me, but the EVO would certainly resolve all my issues with that.
Going back to "quickly." I am a heavy Palm Pre user currently, with the 1ghz processor and 4g data of the EVO I would no longer need to wait to pull up information anywhere information may be stored, whether it's in the phone or on the internet. With that kind of speed I'll most likely cut out an overall wait time of about 30 minutes a day that I would have wasted waiting for my apps to pull up on my Pre. What will I do with that extra half hour, hmmm?????
Ahh yes, and back to my child. I could setup services with Qik and share live video of Lil' Vincent with my parents. That would be so worth it because I live far away from my parents. This would help bring them closer and get a few more peaks of him between our family get togethers.
I know you said share your favorite feature, but the EVO has so many!!! Plus, I was already writing part of my paper for my business writing class. So, I was in the mood for some writing anyway.