RE: Ice Cream Ira's Mixin' Magic
I agree that the rise of new mix-in ice cream chains is curious, especially since the Boston area has had some purveyor of the concept since 1973.
The original (at least in this area) was Steve's Ice Cream in Somerville. Not exactly in a hip neighborhood (at the time) or particularly close to transportation, but had a line practically every night. Ice cream was actually made in small batches in old fashioned tub churns in the front window so flavors changed rapidly. Hot fudge was made in Hobart mixers you could see while in line: butter, chocolate, sugar, pure heaven. Mixins were the primary draw.
Around 1977, Steve Herrel sold the shop and the concept and took some time off, but then returned to the business in 1980 in Northampton with Herrel's. The new owners of Steve's did the expansion thing and had a grocery-store product for a while, but they seem to have slipped out of sight. Herrel's is still around, has a few shops in Massachusetts, and I think still uses the term "smoosh-in" because he sold the "mix-in" concept.