I'd recommend the E51 to be honest, though seeing as it's the phone I've got right now, I'm more than biased
It's got Wi-Fi, 3G and HSDPA, email (admittedly I've never used that features though, just log onto yahoo and check it through the browser). GPS is available, but to get it up and running you'd need to connect it to a separate bluetooth GPS reciever (not supplied)
The camera's awful, but as you've said you didn't need that, then no big deal. The mp3 player's adequate for me using it, though you can install 3rd party apps and everything on it, so you could probably find a decent one if you wanted.
Display is 16 million colours, bout a 2 inch screen, and I think the resolution is 240 by 320, though don't quote me on it.
All specs aside, I bought this purely for the wifi, and I'm definitely not the business user this is marketed at. But, I've gotta say, this is easily the nicest phone I've had, once you get past the learning curve on it, it's a dream to use.
One note, if you're going to use the wi-fi a -lot- then this might not be the best phone for you, as it completely hammers the battery life. If you don't mind charging it once a night though, then it shouldn't be a problem.
ZDNet Review Mobile Phones UK Review Play.com
If you want to know anything else, just let me know, and I'll try and give you an answer about it.
Hope you find a phone that suits you though