Any little flash with an "eye" somewhere on it will have some sort of auto feature. I am sure that there are many options. Just keep your eyes peeled.
I listed a Viv 252 in the classifieds a few weeks ago, along with bunch of other stuff I would like to clear out ((there was a url link here which no longer exists)). This is nice and small, and has M and two autos: orange (8-10 ft.) and blue (15-20 ft.). The original GN was about 55 at ISO 100, according to the distance scale. I don't know what the GN is now, but it does work. It can be triggered via hot shoe or via built-in synch. cable. They should be all over the place and dirt cheap, including on E-Bay.
P.S. Your title for the post caught my eye. Even though we all know what you mean by "strobe" in a photographic context, this is a good thing to know: A "strobe" is a light that flashes repeatedly at a set interval, and is used for various purposes; mainly study of movement via apparent stopping of motion. For instance, it will flash over and over onto a crankshaft turning, or assembly line workers working, appearing to break down the movement into many still pictures, kind of like a cartoon. (Also for entertainment: It makes dancers look like robots! Additionally, they can be used to set the ignition timing on an internal combustion engine.) What you want is an "electronic flash" (or just "flash" nowadays, since the "electronic" can be assumed because those using flashbulbs are few and far between). This is the "correcter" terminology for both on-camera/portable units and for in-studio units. The "strobe" nickname for electronic flash comes from the speed with which it can be used compared to flashbulbs, but is technically incorrect.
