I'd say mine are where the Minis interrupt the wedding by driving through chased by the Mafia and call out 'good luck', also like where Bridger acknowledges the applause of the other inmates after he thinks the plan has gone off without a hitch. The sequence where the Mini hides among all the other Minis in the production line is good. Always thought the 'bloody doors off' bit was good but it's been over-referenced. (Is that a word?) 
The final scene is a classic. I know it was originally written to set up a sequel that never happened but it's become one of the great endings.
I watched that with the Missus recently & she'd never seen it before so watching the last scene was a treat.
That ending's hard to beat, 'I've got an idea...erm...erm' Cue classic soundtrack 'Joong joong, joong joong...' 
Other than Shane, I can't think of a film with such an ambiguous ending.
The other interesting thing about The Italian Job is that it was written by the same guy who wrote the mighty Edge of Darkness, one of the great works of British television.