First time posting, so sorry for any mistakes!
The restaurant booking website is offering 50% off food bills for 35+ restaurants, approximately 25 in Sydney and 10 in Melbourne. Normally they offer 50% off two restaurants in each city per week, but this week is special. Have a scroll through the restaurants - most are good but some are quite high priced or don't have a great review. Note also that 50% off can be only booked on certain days depending on the restaurant.
Secondly, Dimmi is also offering free 'signature' dishes at certain restaurants. Click 'Compliments Of The Chef: SIGNATURE DISH' on the right hand side to find out more information. Unfortunately I'm not sure if there is a min spend or some T&C's, however looking at it, it seems you can just book it without min spend.
Thirdly, they are also offering $29 'express' lunches, however you can be the judge as to whether that's a true bargain or not.
PS. You can sign up and accrue 'points' for every time you dine (and review) - 4 bookings + reviews gets you a $50 voucher (no min spend) to use at selected restaurants.
EDIT: Dates are 11th September to 27th September
EDIT 2: You cannot receive points from Flash specials from 1 August 2015. Thanks @spk
Shame QLD misses out