Can anyone enlighten / remind me - any routes in the northeast where such things might be found? I vaguely recall Cathedral has a few (mordor wall, mines of moria, ?). any others? Dacks? Cannon? whatever?

Relying entirely on memory (a dangerous proposition)...
The Ghost on Cannon, specifically the slab that leads to the Ghost roof.
Something relatively obscure on Cathedral - Don't Fire (Till you see the whites of their eyes) I think, had a very short ladder.

Although not a bolt ladder, when Paul Ross put in The Prow on Cathedral, he kinda intended it to be an easy, practice aid route. He also knew that repeated hammering would destroy the route, so he equipped it with pins and some bolts so that it was about 90% fixed. Very little is fixed today (much of it is C1 anyway) and it probably sees more French free ascents than all-aid. (With the exception of traversing under and turning the triangular roof, the rest of the route goes at a reasonable weekend-warrior grade, esp with a bit of A0 here or there.)

Sente?

The only routes that comes to mind are in the Adirondacks are on the King Wall, like the 2nd pitch of Elusive Dream. When you say "Bolt Ladder" I take it you mean an aid ladder with bolts,rivets, and drilled hooks not just a tightly bolted sport routes, is that what you were asking about? Are you looking for a certain type of aid route?

There's a bolt (or rivet) ladder on BandM cliff. Haven't done it, probably needs some gear to get to the anchor, but many fixed placements in a row. New, shiny, and doesn't seem to be in the book. Bit left of cliff center. No idea of who, the ethics, justification, etc.

There are probably some in bridges or such somewhere.

I was just thinking of a few routes like the west face Leaning Tower in Yosemite etc where a bolt ladder connects some good climbing, wondering if there were anything similar (without requiring the "good climbing") out here. I was kind of thinking of a full-on shiny A0 ladder, but I guess might as well ask re an aid ladder w rivets etc.

Find a big white pine and throw runners over the branches. You should be able to get 8-10 good moves in a row that way.

There's one at Quincy Quarries. No I'm not kidding.

GO

5th pitch of "Leading Cause...." on Owl's Head in Olivarian Notch has about a 10 bolt ladder. it's a dsteep slab and goes free at about 11-.

hm. i assume that just a practice aid ladder, doesn't actually lead to any climbing above?
or is it just really really short?