Look for Golden Tiger, which became The Analyst. Xerox Special Information Systems built it in Smalltalk-80 for the intelligence community in the early 80s, when a spreadsheet alone was still novel. The Analyst was much more: an integrated analyst workbench with word processing, a spreadsheet with multimedia cells and live updates, charts, maps, sketching, outlines, databases, terminal emulation, and an expert-system shell, all hyperlinked and cut-and-pasteable into compound-document reports. It's the most famous full Smalltalk app AFAIK. Absurdly ahead of its time. Some features still aren't matched by Office or Workspace today.
But overall there weren’t many Smalltalk apps for individual users. Most were organizational: JPMorgan (derivatives risk), Orient Overseas Container Line (global shipping logistics), Texas Instruments (fab automation), Deutsche Bahn (scheduling the German railway system). These were complex internal systems built on a graphical, fast-development, integrated platform, when such things were rare and nowhere available off the shelf. Customers often considered them "secret sauce" or strategic differentiators and weren't going to say much about them externally. Vendors were often prohibited from naming customers. As of mid-2025 at least, JPMorgan’s Kapital was still in production, and JPMorgan was still hiring Smalltalk developers for it.
GemStone, the Smalltalk-based object database, had a similar customer list, including JPMorgan Chase, UBS, Siemens, TI, and Florida Power & Light. That's a backend rather than an app, though in the Smalltalk world the line between database and application tiers is much blurrier. Still in use, though ownership has passed through several hands since the 80s.
Many apps not written in Smalltalk per se were direct idea-descendants. NeXTSTEP and WebObjects were built in Objective-C at NeXT, then bought by Apple. (Objective-C was explicitly "let's bring the Smalltalk lessons to a broader world.") In its early days WebObjects could build database-backed GUI and web apps amazingly easily compared to any competitor, and Apple used it for its online store and the iTunes Store. Another cousin was Metaphor Computer Systems. Founded by Xerox veterans, it sold Analyst-like workstations that let brand managers at consumer-goods giants like P&G, General Mills, Pillsbury, and Sara Lee analyze and report on sales and mix data, often pulled from point-of-sale scanners. That level of "what's happening in the field?" integration, in near-real-time (hours not months), with everything pulled together on one screen, was essentially unique at the time. And that users could build their own charts, reports, and workflows without programming? No one else had that either.
So there were notable Smalltalk apps, and many of them operated at substantial scale. They just weren’t consumer apps. And a lot of the direct descendants were much the same.