In HK and the UK, the plates you can have are very limited. Next year though, HK is introducing a new, 8 letter/digit type thing. Any combination you want including spaces!
Anyway, the best plates I have personally seen in the UK and HK that I can remember are...
D1ANA
(UK) On a blue E30 BMW convertible
F355 GTS
(UK) On a, well you guessed it, a blue Ferrari F355 GTS
LE580
(HK) On a Mini Cooper S
HE11
(HK) On a white R34 GT-R
HK 1
(HK) On the richest man in Hong Kong's Bentley
GT1 205
(HK) On a Peugeot 205 GTi (Remember them!)
EL153
(HK) On a silver Lotus Elise
1 6RAM
(UK) On a black Mercedes 500SL
N 8ENN
(UK) On a blacked out green Mercedes M-Class (Nigel Benn's the boxers car I guess)
And my license plate in the UK is pretty cool too, but I'm not telling
Can't think of any more right now.