DSettahr over at Adirondack Forums posted a spreadsheet of all the lean-tos in the Adirondack and Catskill Mountains. He stated it was his “(long term) hiking goal… to spend a night in every single lean-to in the Adirondacks and the Catskills.”
The spreadsheet has two pages: one that has all the lean-tos listed in alphabetical order and one that lists them by the management unit in which they reside. Currently, there are 258 lean-tos on the list. Subsuquent posters noted corrections where lean-tos no longer existed. You can download the file from here or here. You can read the whole discussion here.