Oahu is a very developed tourist destination, sometimes a little over-developed. Sometimes it is hard to choose what to do and not do. There are a ton of people all over the island that are going to want to sell you on something. Some of it may be helpful, others are kinda sketchy.. so use good judgement.

 For vistitors who have been to Hawaii before and are looking for something different away from the group tour bus, then check out this app called "Shaka Guide". Just search the name on any app store. The app works really sweet playing audio narration as you drive the island. Like a tour guide in your phone or something. They have some great driving tours as well as walking tours for the island.  Check them out if you are traveling on a budget but still want a great experience! 

 Some links for free and inexpensive things to do on Oahu

http://gohawaii.about.com/cs/oahuacti...

http://www.hawaiiforvisitors.com/oahu...

Complete Free Things To Do On Oahu @ LookIntoHawaii.com