We've noted in the past that a label on your phone can be a good security tactic, but reader Xponti has another handy phone/label combination: recording those awkward-to-access serial numbers.
As Xponti explains:
I got sick of having to take out my battery on my HTC Desire thus turning it off, every time I had to quote the serial number (it's under the battery). Solution. Get a label maker and tape the serial number on the inside of the cover. That way it is still hidden, but you don't need to turn off the phone and take the battery out to find it.
I keep a note of these kinds of details in my on-phone filing system, but this is definitely a good option to consider, ensuring that the details aren't on display for all to see but can still be accessed. Thanks Xponti!