Many users have problems configuring their special keys in their keyboards. This is specially important for the ones migrating from Windows to Ubuntu: they do expect their keyboard to work in the same way it does under Windows.

Allow the mouse/trackball to be configured for eg left handed use, whilst retaining customary right handed use of the touchpad or second mouse

This would support multiple input devices, each specified differently eg speed, click response, primary/secondary buttons allowing better interaction with shared machines.

Also potentially usefull++ for accessibility where primary user has one input device and assistant/helper can use their preferred device, configured as they would wish

In my case, as a left hander I really like using a MarbleMouse, but the additional buttons are not recognised. As the laptop is moved around, sometimes I have only the touchpad, which, from habit I prefer to have configured with the left button as primary, ie right handed. Also allows me to share machine in these circumstances.

This granularity of HID configuration is available as a third party tool on other OS's. I haven't found anything on Ubuntu to match yet.

As it is, a device (example: cell phone or pendrive) when connected mounts multiple drives if it has multiple partitions.

If you want to unmount a device with multiple partitions, you must unmount each one individually.

The unmount (safely remove hardware) should allow a ONE-CLICK option to unmount the device completely.

See the windows implementation here (with a card reader with 4 particions).
http://softporal.ucoz.ru/Images6/USBSafelyRemove_wm.JPG
http://2.bp.blogspot.com/_ruMCAJda6B0/R4sTELk8_9I/AAAAAAAAABc/Oq8qvjrOLF0/s320/ Portable%2BUSB%2BSafely%2BRemove%2Bv3_3_0_611.png