Found this yesterday and have never seen this type of attachment on one.
What the heck is it for? Drill doesn't work but if anyone wants to tinker with it just pay the shipping and its yours.

I wonder if the shaft oscillates. If so, it could be for valve grinding or lapping.

This is interesting, but not much help.

http://books.google.com/books?id=xCUDAAAAMBAJ&pg=RA1-PA267&lpg=RA1-PA267&dq=Millers+Falls+Dyno+Mite&source=bl&ots=paEZmo-Mjw&sig=O4SFaHeXQ2gW4N7yXag3oSrwcaA&hl=en&sa=X&ei=0DtcUc3JA5Oo4APCp4CYBQ&ved=0CDkQ6AEwAQ#v=onepage&q=Millers%20Falls%20Dyno%20Mite&f=false

http://www.amazon.com/Millers-Falls-Greenfield-Dyno-Mite-Reducer/dp/B005XENOCO

There is a process called orbital riveting where a soft rivet is headed by a tool that orbits while it impacts like a hammer drill. You end up with a rivet that has the shank expanded tightly in the hole and a pretty rounded head. Could the two nibs be fixture guides?

Does this thing work?  Someone needs to go out to the drill gun shed and wake Ron Darner. He must have fallen asleep while he was cataloging his collection.

I plugged it in and squeezed the trigger but there was nothing.
Didn't really look it over real good, just took some pics.

The answer is twelve!  Uh, Patagonia!  Hydrogen peroxide!  Uhh, no ma'am, I wasn't asleep - honest!  I heard every word you said....

On a SLIGHTLY more serious note: I have several MF Dino-Mite drills, and quite a few attachments, but this one is new to me.  Will PM address & info for shipping - I would definitely like to have it.

Yes, I have been cataloging more items, John. Went to an auction Monday (neighbor's estate auction), and bought one lot with four drills in a box, along with a lot of other stuff.  ALL FOUR drills are new models, to me.  One is likely the oldest Millers Falls I've ever seen, and another the oldest Ward's Powr-Kraft.  Adding them to my catalog brought it to the 250 mark (and I'm already higher than that on the conversion tools catalog). Both categories still have piles of stuff awaiting my attention, so the numbers will climb substantially - and there's a huge swap meet the last weekend of April, where I can count on finding more.  Discovered at least one new-to-me BRAND of drill today, which will be #131 on the list.  It is mind boggling, how many brands, manufacturers, options, attachments & conversion tools there are - and I have to assume that I've only uncovered a small part of the entire amount.

There's a patent on the clutch mechanism inside that long front section: US Patent # 2,184,394, issued December 26, 1939 (and corrected Feb. 6, 1940) to Whitfield Moretti for a "Clutch Mechanism."  It was assigned to Millers Falls. See the patent at http://tinyurl.com/bv7ttzz.   
I wouldn't want to say that it's a complicated device - but I did observe a feature or part labelled #599 in the drawings! The clutch offers an adjustable torsion control, as well as a screwdriver depth adjustment.  I am GUESSING that the span across the two pins matches that of Dzus fasteners used in airplane construction, or wherever extremely reliable quick-attach / quick detach mechanisms are needed for cowlings, access panels, etc.  The anchor side is typically attached with two rivets or screws, with about this spacing, and the quarter-turn part is centered between them [USUALLY]. OTOH, the two pins might merely locate the center of a narrow workpiece, exactly as some doweling jigs still do today.
DATAMP refers to this as being part of a power-driven screw gun, which seems exactly right.  However, they don't think it was ever manufactured!!! See http://www.datamp.org/patents/displayPatent.php?pn=2184394&id=24196][url]http://www.datamp.org/patents/displayPatent.php?pn=2184394&id=24196[/url].  I will contact them with an update.

I can imaging how long it would take to assemble that thing, yeash !

Moretti invented one of MF's electric drills, and part of a Jig saw....

Whitfield Moretti designed the very drill that's the basis of the tool that started this thread; the design patent number is right on the nameplate.  Design patents cover the appearance of a thing, rather than its function, while utility patents cover functional aspects (where the term "invent" applies more directly).  Disclaimer: I may be overly sensitive to the difference between "design" and "invent" because I hold only utility patents myself.
Some of the pioneers in power drills held both design AND utility patents: Albertson, Desoutter, Black, Decker, and Wilhide all did, for example.  Looks like we can add Mr. Moretti's name to the list!
The distinctive grooved grip is painted red on this drill, and looks factory.  The cylindrical collar behind the chuck was clearly intended for attachments to clamp onto; on this example, it has been threaded.  The extra feature on the trigger is pivoted on the pin whose end is visible in the main trigger part; it serves to latch the main part "On", and a second pull releases it.  I'll bet that there's a patent on that latching mechanism, just as there is on the bottom-of-the-handle button that Glenn C. Wilhide invented for Black & Decker #2,283,778).  I think that there was already one for the more common side-button latch, and that Wilhide was avoiding it.  This idea would get around both types.  There's another type where the entire trigger rocks to a latched position on some drills, and at least one where a wire bail hooks over the trigger (PET - Portable Electric tools - from Chicago used it).
BTW: in post #6 of this thread, I mentioned having over 130 drill BRANDS identified.  I've been working on that aspect the last several days, and the count is now at 165!  Some a foreign, but quite a few of the additions are American products.  No doubt, many are merely rebadged versions of known manufacturer's products - but not all!

That's a lot of a collection, your electricity must have more pazazz than mine.