Dave's Pin Exchange
A specialist shop in Dolly Sisters, improbably sandwiched in between a house of negotiable affection and a massage parlour. This sort of thing happens: in Good Omens, the parallel is Aziraphale's antiquarian bookshop, which is an incongruous feature in a similar sort of street with similar sorts of neighbours in the Soho district of London (Britain's equivalent of the Whore Pits).
With a jolly notice outside proclaiming the premises as The Home of Acuphilia!!!, Dave's is the sort of shop where the proprietor knows every one of his customers by name. Even so, Stanley is thought of as "a bit weird about pins, to tell you the truth". This provokes a moment of reflection in Moist von Lipwig...
Dave himself is a huge bearded man with dreadlocks, a pin through his nose, a beer belly belonging to three other people, and the words Death or Pins! tattoed on a bicep.
We learn in Thud!, from Nobby Nobbs, that after the stamp collecting craze began to take off, drawing interest from the same obsessive collectors who used to be into acuphilia but have now put childish pins behind them, Dave has now diversified into stamp-collecting and related ephemera. It is unsure what Dave's feelings are on this, but Nobby considers him a friend, or at least a mate. (Could it be that Nobby now has another unlikely seeming hobby - stamp collecting - to go with the morris dancing and historical re-enactment?)
We learnt in Making Money that the premises have since undergone a change of name and are now called Dave's Stamp and Pin Exchange. In The Compleat Ankh-Morpork, the precise location of the business is given as Cripes Alley*(G2), Dolly Sisters. But cross-referencing this to the map, there is no Cripes Alley in Dolly Sisters; there is in fact a street called The Cripes in reference G2. The woodcut advert in The Compleat Ankh-Morpork reproduces the sign hanging outside the shop - this advertises that the Pin Exchange now also accommodates a sub-post office. Good marketing here on the part of Dave, Stanley Howler and Moist von Lipwig?