I've shared these offers under the Vouchers tab, but thought Australia Post' Xmas promo is worth its own deal post as I haven't seen a discount coupon from Booktopia in ages, for example.
1) Free shipping on all Australia Post products. Simply add items to your cart to redeem
2) 10% off at Booktopia with code LITTLEHELPER
Too bad you can't stack this with the free shipping code, and neither does it work if you go through Booko, but it's a rare code which you could use after the free shipping one expires. Also, if you spend over $70 you would save more with this code than with the free shipping one ($6.95).
3) Extra 20% off over 500 items in selected category at COTD. Discount applies at checkout.
4) Save $15 when you spend over $80 at Tinyme with code LITTLEHELPER
5) 5% off everything at Peter's of Kensington with code LITTLEHELPER (no minimum spend applies)
6) Free delivery on orders over $50 at Birdsnest witch code LITTLEHELPER
All of these offers are valid until the 10th of December, but make sure you check Christmas delivery cut off dates at each of the stores (e.g. at Booktopia it's the 8th of Dec.).