There's an adage in the software world: programs should do one thing very well. In that spirit, we offer you a round-up of small and useful programs and resources which do one thing particularly well.
Unpaper is a command line tool designed to correct issues in scanned book pages. It removes excess darkness around edges, rotates and de-skews.
Not a tool, but a resource, The Public Domain Review is a gateway to interesting works in the public domain. Saving you from slogging through all the public domain work available, the Review presents curated collections of particularly interesting work.
Pdf Chain is a convenient addition to another small and useful tool, Pdftk. Pdf Chain provides a graphical interface for the command line power of Pdftk, allowing users to conveniently merge, split and make other modifications to multi-page PDF documents.
GimpLensfun is a handy GIMP plugin using the LensFun library and database. GimpLensFun brings easy correction of lens distortion right into your raster graphics editor.
Gtk Vector Screenshot taking module does what it says on the tin: it takes vector-based screenshots. No more flat, un-scalable screenshots.