Thanks to Digidave for inadvertently suggesting the revised title.
So after I whined a little about the lack of comments on Part 2, you all really reinforced my bad behavior by piling them on.

Thank you kindly, and so here we are with Part 3. If you missed the first two, check out
Part 1 and
Part 2 for a little background about what my intentions are with this series.
We're almost up to Christmas (where I'll get a second speedlight!) but before the big day we all took a road trip with my wife's family to see some cousins and her grandmother. This was to be my first time shooting any more than two people, so I had to come up with some new techniques.
So what to do with 11 people and one little speedlight? I decided to use the sun as my second light as it was free and did not require any odd battery sizes. The idea here is detailed by the Strobist article from Lighting 102 about
crosslighting with flash and sun. Go give it a look, as Mr. Hobby explains it much better than I can.
Tired of me yapping? Here is a test shot I took after setting up my bare strobe 180 degrees from the sun. That means that the strobe is hitting them at about 45 degrees with the sun directly across from it. The subjects are my wife and her brother.
Note: Click on any picture for a larger version.
As it turns out, this was my favorite from the whole bunch. The SB-600 was firing at about 1/8-1/4 power at f/5.6. My shutter is at 1/100 to get the right amount of sunlight in the exposure. If I had it to do over I would have them trade places, because her black shirt gets lost on the dark background and she could use the added rimlight from being on the other side. Alternatively, I could have used a reflector or another strobe behind her for some backlight to give her left shoulder (camera right) more definition.
So, lets add a couple of cousins and a grandma:
This was shot less than two minutes after the first one, so the sun had not changed much (but it was going down). I had to reposition the flash, which forced me to power it up some more. The whole thing looked a little overexposed and I wanted a little more DOF so I solved both problems by changing my aperture to f/6.3. Notice that the dominant nose shadow is on their right (camera left), so I would say the flash here is the key (main) light and the sun is working as fill and rimlight.
So up until here I had been able to squeeze the various groups in front of that lovely magnolia that has been working as a backdrop. With everyone in the photo, that wasn't possible. Here's the obligatory family group photo:
It's only 9 minutes from when I took that first test shot, but the sun has gone down enough that I need to slow my shutter to 1/50. I left the aperture at f/6.3 for fear that any less DOF would not get both rows in focus, and the flash was on 1/2 or full power and moved back to avoid grossly overexposing the person farthest camera right.
This shot is FAR from great. But I also think it's a heck of a lot better than your average frontal flash group shot from the holidays. The people standing at camera left have more sunlight on them, and the people kneeling at camera right have more flash lighting, but they are all very close to the same exposure. And the quality of the light is fairly interesting too.
Oh yea -- I definitely should have asked the back row to move over by one person, but sometimes you have to balance getting things right with driving your family completely nuts.
Lessons Learned (or at least reinforced):
--You can light 11 people with one strobe (and the sun).
--Afternoon sunlight changes fast, but shooting in manual and slowly decreasing shutter speed gives you lots of control over this.
--Check to see if the grass is wet
before you ask everyone to kneel down. Oops.
--Always check your background, even if 10 people are waiting on you.
--Crosslighting is easy.
Please feel free to comment on the series, this post, or any individual picture. My hope is that watching me fumble through the process of learning portrait lighting will help some folks out and encourage the hesitant to try this with your own families. It's lots of fun.
Part 1 -- Umbrella Specular
Part 2 -- Adding a reflector for fill (and a Mother-in-law)
Part 3 -- Crosslighting with the sun (for a group portrait)
Part 4 -- Now I have two strobes!
Part 5 -- Ghetto striplight high key fun
Part 6 -- DIY Softbox for serious light