Bluelog is a Bluetooth site survey tool, designed to tell you how many discoverable devices there are in an area as quickly as possible. Bluelog differs from most Bluetooth scanners in that it prioritizes speed of reporting over anything else (i.e. it doesn't spend time trying to pull detailed data from a device) and doesn't require any user intervention to function. As the name implies, its primary function is to log discovered devices to file rather than to be used interactively. Bluelog could run on a system unattended for long periods of time to collect data. In addition to basic scanning, Bluelog also has a unique feature called "Bluelog Live", which puts results in a constantly updating Web page which you can serve with your HTTP daemon of choice.
Analog PHP is a short and simple logging package for PHP 5.3+ based around the idea of using closures for configurability and extensibility. It functions as a static class, but you can completely control the handling of log messages through closures (aka anonymous functions), and it also comes with a dozen pre-written handlers. It is well-documented, with examples for each type of log handler, and ultra-concise. The core is literally only 43 lines of clear, non-obfuscated code, and the whole is only a fraction of the size of comparable packages (for example, 293 total lines vs 1021 for Monolog).
JCabi is a collection of small, useful Java components. It includes a convenient static wrapper around SLF4J, a Sonatype Aether adapter, an Amazon Elastic Beanstalk Maven plugin for seamless deployment of artifacts, a Heroku Maven plugin, a Maven Log to SLF4J binding, and a few others.
OnPosix is a tiny library to abstract POSIX mechanisms to C++ developers. Most features offered by this library can be found either inside the Boost library or in a library compliant with the C++11 standard. Unfortunately, however, for some embedded Linux devices, these libraries cannot represent viable solutions, due to the lack of memory space (for the Boost libraries) and the lack of a new C++ compiler (e.g., on Xilinx MicroBlaze). On these platforms, the OnPosix library represents a good and cheap solution to have object-oriented POSIX mechanisms. The library offers support for threads, mutual exclusion, sockets, logging, timing, etc.
ZedLog is a robust cross-platform input logging tool (A.K.A., a key logger). It is based on a flexible data logging system which makes it easy to get the required data. It features logging of all keyboard and mouse events, a replay simulation tool, logging to a file, and hiding in the background.