The following businesses offer free wi-fi for customers in the Cairns district:

Cairns Library - offers connection to  Cairns Community Wifi - 100MB download limit per day.  If a Library member you get 200MB. Available from Library on Abbot St and in some areas around the Esplanade

Xtreme Travel and TOUR SHOP.com.au - offers fast free internet to their travel customers. The first internet cafe and travel agent to offer the fastest wifi hotspot in Cairns... Located opposit the Night Markets at 129 Abbott Street Cairns.

Visit Cairns  - Offers free wifi for travellers staying in Holloways Beach. You might be able to get signal staying at Machans Beach too.

The Tour Company - Cairns Visitor Information an Booking Centre - located at Shop 5B 103 The Esplanade, Cairns City (Between BarnacleBills and Movenpcik ice cream) Look for the big flag with the big blue i .   Here you get FREE Unlimited WiFi and can also borrow an iPad to use for FREE.  The staff are also very handy for all the info you need on travel in Australia.  

12 BC or Twelve BC - Coffee shop at City Place. Cnr Shields and Lake Street. Free Wireless plus some of the best coffee in town as well. Coffee about $3-$4. Have cafe type meals and snacks.

McDonalds - As they do countrywide free wi-fi is available at all their restaurants. McDonalds is located on the Esplanade on the corner of Shield Street in downtown Cairns. There are several other outlets in suburban Cairns.

Blue Sky Brewery - They also have some great deals on snacks like $2 Taco Tuesdays, and local brewed ales of course.

The Chocolate Room - 11 Grafton Street (near Shield). 

Hot Air Balloon Cairns - has free wifi on all of its 6 transfer buses from Port Dougals and Cairns daily and with an hour to travel along the way you can easily catup on emails, Facebook and post images as you transfer to the daily balloon flights  

Accommodation with Free Internet - Use the "Free Wifi" button under the "Amenities" tab.

You can check with other hotels if they have free internet. For example: reviews suggest  that Novtoel Cairns has free wi-fi in pool bar area, and Hilton promotions offer free wi-fi in their business centres.

Your own phone and data connection

For extended trips purchasing pre-paid system may be worthwhile. Hotel rates can be expensive and will usually justify the cost of a sim card for your phone or modem. The best coverage is offered by Telstra if travelling to remote areas.  Otherwise Optus is good.  For more information on sim card options, read this page.