I recently bought an N810 because I felt it was an amazing piece of hardware supported by a mostly open source community. So far have I not been disappointed, but like everything, it can always be better:

A) Change the memory/filesystem layout to be as follows:

Internal "MTD" memory to be used for bootloaders, recovery utils, & misc diagnostics only. The boot loader should have adequate options for any future OS's including those not sanctioned by Nokia. The recovery utilities should at the very least allow for complete rebuilding/installation of Nokia OS on the MicroSD listed below. Other diagnostics should help troubleshoot possible hardware problems that might be confused with software or OS problems.

OS then lives on a removable MicroSD. This can be located in a less accessible area such as in the battery compartment. Ship the unit with a microSD and OS pre-installed on it. The size should be such that there is enough room for the OS, map data and a reasonable amount of user files. Users can upgrade to larger microSD disks if they wish. This arrangement makes backups, alternative OS/versions, disaster recovery, easy by just plugging in different cards and booting or restoring. The MicroSD should probably have a native Linux file system on it.

If possible, go back to a single full sized SD slot for the "removable" memory.

I feel this arrangement makes the most sense in that it provides "bricking" prevention by discouraging modifications to the internal MTD memory, removes memory wear issues by putting everything else on removable (as in replaceable) memory cards while providing for a large enough, and expandable root file system, then providing a more industry standard and larger capacity potential removable storage.

B) As others mentioned, USB charging would be nice, but these are the issues with it as I understand:

1) USB Current is limited to 500ma. This means a slow charge rate. A very slow charge rate if unit is then in a high battery-drain mode at the same time.

2) Will there be a problem with polarity reversal going from USB host to client modes? Hopefully there already safeguards built in the existing units to prevent damage to the IT or USB devices.

3) If USB charging is worked out, it might be decided to eliminate the tiny Nokia power connector and charge the unit from USB only. In this case the USB micro-to-"A" adapter cable should be modified to accept the charger (perhaps a from a standard USB "A") while providing a separate "A" connector for USB accessories. Perhaps the charger can then provide a true 5V USB power to the accessory when operated in this mode? If the dual "A" cable arrangement is chosen, then the unit could accept two USB devices when running from batteries only, assuming there is enough power to run both of them.

C) More RAM memory. 256 Megs would be very nice and speed unit up a little too since Linux has a good memory caching scheme.

D) A better camera, but with more efficient processor support so that when used as a web cam, it doesn't use up all the processor power. Perhaps it can get help from the DSP module in the OMAP? A higher resolution camera could then do "face" or "motion" tracking to produce a lower resolution window "cut-out" of the full image to stream. This would be real slick!

E) Increase the battery life. One of the reasons I chose to purchase an N810 over an ASUS EEE-PC was battery life (It sucks on the Asus). The goal should be to make the unit last a day with normal use. Can this be done with better power management and/or by the use of multicore processors? Of course I realize that LCD backlighting is one of the most major power drains, and perhaps not much can be done here unless there are some breakthroughs in LCD & LED technologies. For those wishing for inductive charging, I doubt we have room for enough iron core to be able to transfer enough power, but I could be wrong.

F) Put more buttons on the front of the unit. Make some of them a little easier to push for better game playing.

G) Either make the handwriting work without having to shift for different charactor/symbol sets, or eliminate it completely. It is not very useable as it is. How about some voice recognition software instead?

F) Choose hardware that we can have fully open-source driver access to. Proprietary binary drivers are very troublesome for a Linux system in the long term and should not be used.

G) If you choose to install a "real" mobile phone radio, make sure it is an open source supported one. Do not make "deals" with service providers like Apple did. Notice I purchased an N810, not an Apple iPhone or ipod-Touch!

H) Although the size of the device (N810) is just about perfect for me, if a slightly larger display can be squeezed into the N900 without making the whole thing much bigger, let's do it. If you do make the whole unit a little bigger, put in a bigger battery. Others have said that the size of the original N770 was good. Maybe so if it is filled up with a larger screen and enough battery to power it.

I) Move the +/-/FS buttons so that they are easier to use when keyboard is extended

J) Do a multitouch touch screen unless Apple has it too patent encumbered.

K) Change the mobile mount to be a window mount (like the Nokia HH-12), the built-in GPS receiver needs to be up at the window to be useful.

----

Things to not mess up:

A) Sound is great for such a small device. Leave it alone. I also like the standard-compatible 3.5mm headphone jack with the optional 4th terminal microphone capability. The inclusion of speakers set this product apart from the many "Video-MP3" players that are out there. Keep all this.

B) Keep the role switching host-mode / client-mode USB port

C) Keep the GPS receiver, make improvements to it if you can

D) Keep a physical keyboard, but entertain better ways to do it.

E) Keep Bluetooth

F) Keep the kickstand or at least something that performs this same function.

G) keep the stylus & cradle for it.

H) Keep the unit rugged.

-------

Things I don't care about:

A) I personally don't care about the FM radio (either receiver or the mythical transmitter)

B) The soft case (as compared to the older hard one) is just fine with me too. The hard case just makes the unit bigger in practice. The soft case protects the unit from scratching, the rest of the unit is rugged enough to not need a hard case.

C) I don't think I care about all that auto-rotating screen and accelerometer stuff that Apple uses. It seems like it was be a processor-intensive annoyance in the long run.