The 'phone' (rather than PDA) that has most features, including things like battery life is the Ericsson T68. It literally has every mobile phone technology currently available - bluetooth, irda, wap, gprs, colour, etc, etc.
Yes, I do own one, No I'm not plugging it : whilst it does have all these gimmicks, I've had nothing but trouble with it every since I bought the damn thing - I'm now on the third handset and it still struggles to make something as simple as a phone call !! So, the moral is, whilst something may appear to be great, it's most likely a pile of...