Posting here as not a specific bargain as such:
DropIt runs reverse auctions for various items and gift cards throughout the day, including $50, $100 & $200 gift cards for the major supermarkets and petrol stations, as well as Visa Prezzy cards. Gift cards generally sell for 8-12% discount from their value ($100 for $88-92), and are the exact same as you'd by from the store (usual T&C's apply).
Auctions run every 2 minutes through the day - price drops from RRP and keeps going down until the first person 'swipes up' and gets it at that price. Courier is free, and most gift cards show up within 3-5 days. I've been using for over a year now, and purchased 60+ gift cards for all my spending - easy way to save money.
Have to download Android/iPhone app.
See affiliate page to get $5 off first purchase.
Stuff article has a bit more info about it and shows its a genuine site.