Uber is relatively new to Brisbane… although the free rides have now stopped you are able to get $20 free credit toward your first ride by using the coupon 'tryuberbris' on signup.
If you already have an account or errors out suggesting a code has already been applied - change the mobile number listed in your profile (i'd suggest adding an additional digit to the end) and sign up again.
Make sure you change TAXI gratuity to 0% as it is set as default to 20% of metered fare
edit: TRYUBERBNE added as per https://twitter.com/Uber_Brisbane/status/485254686748848129
Qld cracks down on Uber taxi service
http://www.news.com.au/national/breaking-news/qld-premier-gi…