First three and the last picture were taken with a point and shoot pentax optio WP, the old 5mp model. I just have the flash settings on soft to get a nice fill in - reduce the shadow in the harsh light and 'pop' the fish. I'll usually fire a bunch of shots, as it is amazing how the fish an look so different from one picture to another. I also find the best pics come from the height the fish is being held at or below. I love the perspective looking up shots give. Matt took the pic of me, the tuna and the broken rod using my camera, set up the way I like to use it..
The others were taken by Nat Bromhead on a Nikon D70s with some pretty pricey lenses.
I think Jim was shooting his with the new waterproof Olympus Mju 720 with 7mp.