Car reg + serial number
In the UK at least the combination of a neighbours car number and the model number on a bit of equipment is likely to be secure and yet still easy to use.
An example (not one that I use!!!)
S357HGKAOA110Ab where S357HGK is a car registration number and AOA110Ab is the model number of a netbook.
(The car reg number above is a made up number - I do not know if it is still in use.)