Playing with G-INFO whilst waiting on hold on phone with a company.
Some registrations that don't appear to have been issued. Feel free to use on your fleet:
G-AUDY
G-OGGO just to annoy ATCOs, though I see G-OGOG was on an R22
G-OZER I ain't afraid of no ghost
G-OBOX for a Skyvan to follow G-OVAN
G-ONGO one for a charity
G-RIMY if only Air France used G regs
G-ULAG might suit an imported
TupolevG-USHY
G-YBED "changed course by swinging the sail across a following wind"
oh 'Will' answers my call and apologises for the long wait