Hey Westy I have a couple of apps for you that are pricless.

First one is Wikicamps. It looks like google maps but with every thing from roadside camps, to bush camp sites, to caravan parks. It has so much information about each different one. Also has a comments section for more info.

Second app is called Fuel map by wikicamps.
This one tells you what the fuel price and brand is at any servo you will come across. It relies on people updating the price when they are there so in more remote areas it is not quite as good but will still give you an idea. An example would be to seach Glendamo. It will say BP $1.57.9 2 days ago. Saved us a bit of money when we went to uluru. Big roadhouse at Urldundra which is the turn off to Uluru was 2 bucks a litre but little roadhouse 50ks further down the road was 1.60. It also has a cool feature which you put in your details when you fill up and it calculates your economy, averages and totals for your liters and dollers.

FYI mate we did 6,500kms, averaged 17/100 and spent $1400 on fuel.
Hope this helps a bit mate