I'm a computer science student from the Netherlands, I haven't a bought a Neo yet, I will probably wait for the v2 (I want Wifi and an accelerometer, and the rest isn't too bad either).
I'm definitely going to add some I2C sensors:
- a compass for various purposes, it could integrate well with quite some applications I think (if it isn't added to the v2 already... hope hope).
- a barometer/altimeter so I can really measure the height differences in our flat country, and the tide, and also for paragliding (variometer).
- I like the idea of a Side-Mounted Touch Strip too, I think there's some place behind the front plate where it may fit.
While the barometers purpose will be probably a simple vario/heigth meter application, and the touch strip driver may be implemented as X11 mouse/keyboard driver, the compass really adds a lot of possibilities for everyone, so I really think it's a good idea to add it to the standard Neo.
Also I have plans for building a 2xAA (maybe 4xAA) powered USB hub with embedded AA charger and Neo charger on 12V and/or 5V power. This device should have a dedicated Neo USB cable, some USB ports and a power hole. If it is powered the AA's will be charged, the USB ports will be powered and the Neo USB cable will be powered. If no power is attached the AA's will just power the USB ports. If your Neo needs power in case of emergency you can always plug the 'Neo to Computer' USB cable into the hub and charge the Neo from AA's.