Off the top of my head, Pandoc, a tool for converting between different markup/down flavors, and xmonad, a tiling window manager for linux. Both are well known and popular.
Also found it crashed a lot, which I would have hoped would be one of the things Haskell would solve (the problems revolved it having to integrate into C code for linking to X, but that's part of living in the real world).
Complex transformations of data structures are part of the compilation activity too, but they're more difficult to spot in the wild of applications.
You can create your own document templates, and tweak the resulting output in a million ways. At my job, I have to create a lot of documentation, often in PDF or docx, and Pandoc has become an integral part of my workflow. I can create documents within the comfortable environment of Emacs, and use Pandoc to produce output in any old format that $pointy_haired_boss may desire.