For the next three weeks, Virgin Mobile are engaging in a social media inititive that has pretty fun real world results: they've stashed 75 bicycles around Australia, and they'll be giving away 25 of them a week.

The competition is called 'A Fair Ride for All', and as you can see from our gallery,  the bikes that they've chosen are all very much worth hunting for. Priced between $600-$1500 a pop, they've selected various different sorts, from fixies to mountain bikes, and will be distributing them across Sydney, Melbourne, Brisbane, Perth and Adelaide as they see fit. Today's Sydney offering was a single gear, that was found in Chippendale's Victoria's Park, while the Melbourne bike (also a single gear), is somewhere around St Kilda. From the latest photo clue Virgin have posted, we're pretty sure it is stashed in Luna Park.

The giveaways are only happening during the week, with one bike being released in each city each day, so going bicycle treasure hunting could be a particularly excellent hobby to take up if you're currently unemployed or on holiday.

To take part in the bicycle treasure hunt, visit the Virgin's specially set-up website, then select your state and follow the competition's clues.

As far as branded giveaways go, this has to be one of our favourites this year.