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.

http://unpaper.berlios.de

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.

http://publicdomainreview.org

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.

http://pdfchain.sourceforge.net

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.

http://lensfun.sebastiankraft.net

Gtk Vector Screenshot taking module does what it says on the tin: it takes vector-based screenshots. No more flat, un-scalable screenshots.

https://gitorious.org/gtk-vector-screenshot