The thing is bulky because you're getting a full VGA display and a reasonably-sized QWERTY keyboard. If these are selling points for you, you're kinda out of luck. You can get smaller (something like a Treo, or a Sidekick) or less display (a Nokia 9300 has the keyboard, but a narrower display). I'm also guessing you want more of a phone than a small laptop.
I am a hair away from biting the bullet and buying a HTC Universal (probably from Orange here in Switzerland)--it has all that I need/want for a PDA phone (3G, gprs, wifi, gps expandable, qwerty, ms 5 mobile), but I hesitate to buy something that looks like such a brick.
Is there anything out there on the short term horizon that comes close to the attributes of the Universal but is a bit more compact/slimmer??