I recently purchased a Nokia 770 Internet Tablet. This is a handy device but can be a little confusing. It is not technically a phone. That means, you can not use it as a replacement for your current phone, as it does not talk to cellphone networks (i.e. Sprint, Verizon). It does have Bluetooth capabilities and 802.11G support for wireless networks. These capabilities allow you to leverage you cellphone and home networks to give the 770 Internet access. In the case of cellphones, this would be known as tethering. You should make sure your calling plan supports unlimited data and tethering, otherwise you may receive a nasty bill.
The 770's screen is ~4.7 inches and supports a resolution of 800x480. I was pretty impressed with the quality and brightness of the screen. It is also a touch pad, which works nicely with the included stylus.
The operating system is based off of Linux, so no windows apps here. If you need a windows environment, there is a solution. There is a RDesktop port available at this link. RDesktop will allow you to connect to your windows system and have a desktop on the 770. It works well, although there can be some window sizing issues. VNC is an alternative to RDesktop and there is a client for that too.
There is a lot to talk about with the 770, so I will continue soon.
The 770 is not the latest version from Nokia, that would be the N800. That means the 770's can be had for a good price. You can read reviews and get more info from the Amazon link below, but you can probably find a better price elsewhere.
(post from an old blog attempt)
Nokia 770 at Amazon