Maggies walking across a lawn, listening for grubs to pounce on.
Their warbling and carolling (and the persistent nagging call of young begging for food) is unmistakeable. I've no doubt it is a sound unique to Australia that is much missed by many expats. What they won't miss is the occasional male Magpie whose testosterone rages out of control, causing him to attack pedestrians and cyclists within 100 m of the nest. Whenever one of these rogues moves in to the neighbourhood, walkers are well advised to wear hats with fake eyes painted on them and cyclists need to attach cable tie spikes to their helmets like this if they are to avoid being violently dive bombed and pecked. It's enough to make a kid take the extra long way round to and from school, I can tell you. Ian Fraser, over on Talking Naturally, points out that this strong black and white coloration often indicates a creature is agressive.
PS: When I was searching for recordings of magpies calling I came across some birdsong ringtones for mobile phones -- I am so tempted to get the maggie one!