Nokia N810 4.13" Tablet

The N810 is a Linux laptop computer. You place applets on the desktop for items you want displayed continuously (time, calendar, weather, etc).  There are quite a few programs available for it, although it helps to be a little computer savy to find and add the catalogs (repositories). This little computer functions very well as a 1) media player - both music and video 2) gps unit. I wouldn't buy either of these when you could just get an N810.
Attributes:
- Nice size display for a PDA. 4"
- Linux OS
- Built in GPS receiver
- Bluetooth
- 2 internal memory chips, 256MB and 2GB. I recommend implementing an extra 128MB of swap. If you do this through the control panel, it will use the onboard 2GB. If you know how to create swap using linux sysadmin ability, you can create the swap on the microSD card.
- Mini and Micro (with mini adapter) SD cards.
- USB  pc connection (although with program it can be used as a host USB).
- Slide out keyboard
- Good battery life
- Touch screen with handwriting recognition
- Camera, microphone, and speakers. Intended for video conferencing.
Limitations:
- 256MB of RAM. You can run a bunch of small applications, but if you want to run something of a memory hog, it has to shut down applications to do it. You can create swap memory of 128MB on internal memory, though.
- WiFi access only. Althogh there are a lot of access points avaiable that people leave unsecured. There's a much more expensive N810 model that uses Wi-max but I believe that is only available in certain cities.
- good size keyboard, but keys keys are smooth and only slightly raised in the center, so it's tough to type quickly sometimes.
- Since the camera and display face the same direction, it's not all that good for the basic camera application.
- non-standard linux on non-x86 chip. This means it's not so easy to download any linux program. If you actually wanted to build some open source package, you need to install an OS2008 virtual machine and then compile programs in the virtual machine. Then you can port the program to the N810.
Installed Applications: Web browser, GPS mapping, email, to do list, rss reader, chat, file manager, notes, pdf reader, xterm, control panel, application manager, basic games, media player, audio recorder.
Available Applications: GPS navigation, VPN, Remote Desktop, Calendar utilities, Skype, Camera, weather applet, GPE summary applet (calendar/to-do summary), almost any linux program that has a small memory footprint.

Specific applications notes:
Map - the GPS mapping program that comes built in is only for mapping, not navigation. Navigation is for the live "turn left here" kind of stuff with audio. The Navigation can be purchased for about $120 for 3 years. I used the 1 week trial and it worked good. One issue is that the maps occupy most of the space on the internal drive. I moved most of the maps to my removable SD card and the program automatically recognized it, which was nice.

Maemo Mapper - this is a free mapping and navigation tool. You need to download the maps before getting in the car, however.
If you have a "tether" cell phone data plan, it's possible you can connect to the internet while driving and have it automatically download the maps. Another issue is granularity (called levels). I downloaded the southern california area at "level 6". This was about 180MB and showed streets pretty decent. I couldn't pre-download all levels because it would have been hundreds of Gigabytes. I had to download the voice synthesizer for a previous version of the OS for it to work. This was a bit of a pain to find. It helps being linux-savy.

Media Player - I haven't used it much for mp3s. What I have used it for is mp4s. I burned some of the movie DVDs I have to mp4 and the picture is great. You should close other apps to view a movie. No need to buy an ipod.

Browser - the built in browser is fairly decent, but too much javascript will make it bog down. Zillow.com just doesn't work that well. I downloaded the Midori browser just to browser "heavy" sites.

Chat - worked fine the few times i used it.

Games - most simple games play fine. I downloaded freeciv which really tasks the machine at 256MB RAM. It crashes a lot. I have to make sure nothing else is running and I sometimes kill a few processes. I reboot after playing.

Overall: this is a great little machine. Especially if you are familiar with linux. If you aren't then it's still a good machine, you just won't be downloading the extra goodies. This really beats a GPS machine or a MP3/Video player hands down. I purchased mine on buy.com for $200.