We are traveling to Hawaii in July. We need a flight from Oahu to the Big Island for five days and the the Big Island to Kauai for seven days. Then Kauai back to Oahu for the flight home. Is there any special place to look for these flights? Any suggestions? I am just not sure what to do.....I realize that I probably should have booked the flight out of Kauai, but we did want to go to Oahu on the front end for a few days to see Pearl Harbor and I got a good deal from Charlotte to Oahu RT.
We don't go until July of 2012 but I am not sure if I need to start looking now.
Thanks for any help!

Relax, you have plenty of time to book. Try Hawaiian Airlines, travelocity, expedia, orbitz, kayak, etc.

Nice and informative

cheapoair.com

kayak.com/buzz

best values

book on late Jan Tues PM the drop price a lot

farecompare.com good tips on this

There are plenty of interisland flights each day. Aas said above, you have plenty of time to book. Check Hawaiian Airlines' website, kayak.com, and any of the other travel booking sites. I'd wait a few months.

Thank you all for your help and advice! I really do appreciate it!

Have you already booked main flights over and back?
If not, consider doing an open jaw ticket so you don't have to backtrack to Oahu. You might need to re-order the island visit order, but it can save you money and also give a you some extra time on one the last island.