So far, every picture that Pat or I have taken since we started going the digital route underwater has been with the onboard flash or with available light. We both now have Canon G9 camera setups and decided that we'll take the opportunity of the stimulus windfall to pick up the Ikelite strobe package linked here:
This strobe isn't a high end strobe package, but it packs a fair punch for the price and might be ideal for our use. I'd been curious about it, as it offers a decent amount of power for macro and nearby pictures, say to about 3-4 feet, for the price. It just came out in the last couple of months so there's not a lot of them out there just yet, but a customer the other week had one and is quite happy with it so far. It's made to be compatible with most of the point and shoot camera setups currently available and has a sensor to make it more or less automatic once you get settings that give you an exposure you are comfortable with. Few, if any, strobe packages give you this much strobe, along with a tray and sensors, for the price.
We'll probably take the plunge in the next few days, then have it by the end of next week and be mad we even bought it after the first use or two or three.... unfortunately, with new cameras and such, it takes a while to actually figure out how best to use what you just picked up. I've "upgraded" 4 times now since getting into the underwater photography thing and each time I wonder if I hadn't made a mistake at first, only to figure out what I'm doing wrong and ending up happy after all. I'll let you know how it turns out.