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).
