I don't use any strobe with mine and am not planning on buying one. I know that some divers are using an HID light with their cameras. SIcne I plan on using it only gor freediving I want to keep it small.
I have freedove once with a housed Nikon F4 with two Ikelite storbes on it. I had it dowj to 65' and almost had to leave it there.
Since it wasn't mine I kicked it bck up with everything that I had left in me, after taking a few photos of a shipwreck with it first.
I decided after that to keep my camera set up as small as possible.
They do make digital strobes that will go with the camera adn Olympus housing. The DIgital diver forum will have more info for you about which ones are best. I have heard some horror stories form other divers that I know about didigtla strobes "smoking" underwater!:waterwork
I bought a 512mb Cf card for my camera off of Ebay, Ted has they site, and it now allows me to do 25 minutes of video, 32 exposures on the highest TIFF rating, or 5,000+ pictures at my lowest rating.
My next purchase, after I sell some doubles
, is an Olympus wide angle lens that will screw on to the outer ring of the housing. When it comes to underwater pictures, especially in BAD vis, the wider the lens the better.