Thanks Sean, you can get a lot of great information right off Scuba Board. This place is great and I learn more everytime I visit. Go especially to the Oly Outlet and do a search for 5050 and 8080, lots of good info.
That said, a couple of general things to keep in mind since you are using the internal flash are:
1. Get very close to the subject to take advantage of the light output of your flash.
2. Don't get frustrated at first when you see the lens port shadow when you are too close. You will have to train yourself to judge the right distance and will most likely have to take several shots until you fine tune the right range to avoid the housing shadow.
3. Set up a mode for supermacro with the internal strobe on slave at 9-10 intensity. The only way for the strobe to work in supermacro is on slave. If I recall, this is not in the manual. I learned about that on SB. I like to frame my supermacro shots with a dark background and usually leave my shutterspeed at 400-1000 and play with f-stops in the 4-8 range. By all means experiment with diferent shutter speeds and aperatures to get a feel for what they do to the shot. A lot of the learning comes when you have the pics in your computer and you compare the results you get from different settings.
4. Try out macro shots too. In macro you can get pretty close to your subject while zooming out. This allows you to get more surrounding scenery within the internal strobe's close range.
5. Set up a mode for manual white balance work with something like 125 f-stop and 4-5 aperature with the flash turned off for shallow water shots. This will allow you to use ambient light for wide angle shots.
Have fun!!!