My 2 cents worth (and that's about all it's worth!) -

I had a n800 and replaced it with a n810, mostly for the keyboard. I find it does all of the things you mention above quite well. I use the device on a daily basis for web, email, and reading rss feeds.

For a cell phone I have a Blackberry Bold. Wonderful device. Wifi, 3G, camera, KEYBOARD, gorgeous screen, etc. Because of the two radios (3G amd WiFi), I can take it pretty much anywhere and still access all the information I need. The screen is not nearly as big as the n8X0's, but it gets the job done when there is no WiFi available.

I recently bought an iPod Touch. I resisted for a long time, and I refused to get an iPhone (or any phone without a real keyboard). I have had several in the past (a Siemens WinCE for instance) and the lack of a real keyboard really sucked for me. I have to say I love the Touch for it's simplicity and it really cool touch screen. The availability of apps is amazing (even if a lot of them are useless - how many fart apps does one need?). It does many thing remarkably well, including play music and videos, and YouTube videos. However, it is far from perfect, and only reinforces my decision NOT to buy an iPhone.

The first demerit with the iPhone/iTouch is the virtual keyboard. In a word, it sucks. Most of the time you are forced to use it in portrait mode, which causes the "keys" to be really small. Predictive text, while it is there, never ever seems to help me. Ever. Also, depending on the app, the keyboard is not always the same layout. In some apps this is good, but in others I think "why is the other layout not here?" I constantly have to retype things --- and passwords are especially bad since it hides the text rather quickly. Typing fast is almost impossible.
The other thing I have noticed, is that programs crash on it rather frequently. It is a fairly graceful crash, with the app just closing back to the main menu. With no explanation, error code, etc. iTunes does offer to send the logs back to Apple upon the next sync.

Over all, I like it as an internet device. The screen is much smaller than the n810, but zooming is fairly easy (it could be improved). The keyboard sucks (would much rather have the n8x0's virtual keyboard's predictive text feature --- which actually works pretty well).

For a phone, I cannot recommend an iPhone. I have many friends that have them and like them, but for me a good keyboard is a must. I live with email and texting more than voice calls. The BlackBerry, the Palm Pre or one of the high end Nokia's fit this bill to a T for me.

For an mobile interenet appliance, botht the n8x0 devices and the Touch work well in their respective ways. The Nokia seems much more business like and has a much larger/higher res screen. I can actually do work on the device.

The Touch is great for a quick web visit, or if there is an app, then you are in business. But the screen is small (but very responsive) and using it to do work (without a custom app) can be frustrating with the tiny screen. It has some really awesome games however.

Well, that's my two cents worth... hope you find something of value in there! Good luck!