Google Android
I got my first smart phone about 2 years ago. It was the UTStarcom 6700, a rebranded HTC Apache. I used it for ~8 months and was a big fan of the phone but it had major battery issues, and even getting a replacement battery didn't seem to help. So I finally got fed up and took advantage of a Blackberry Pearl promotion. Since then, my HTC has sat, untouched. Recently I contemplated installing some sort of Linux on it, and using it as a PDA. It has a large touch screen, a slide out keyboard (that I find rather useable) and WiFi. Then I stumbled across this website, where someone is building Android for the Apache.
The project is still in alpha, and while it states that CDMA is working, the currently release doesn't seem to have working CDMA (I eagerly await the next release). Anyways, I installed it and played and I must say I'm rather impressed with Android. I'd imagine on a phone that's been engineered for it, it's probably amazing. Even on the Apache it looks and feels great. I imagine if I used an iPhone that I'd see these similar slide menus, but I have, so far, successfully stayed away from the iPhone.
Once this build gets to be further along, I think I'll be fairly happy with it. It's fast and looks great. I may even go find a extended battery and carry it instead of my blackberry.