A Single-File-Script For PHP Debugging: PHP Bug Lost
PHP Bug Lost is a free and open source script for debugging and monitoring PHP code.
It is a one-file-script, works by inserting a function inside web pages and displays the information in a console window right over the web page.
The script can present custom logs, SQL queries, variables, Ajax queries and measure loading times + CPU/memory usage.
PHP Bug Lost is not only built to be used in the development environment but it can also be set to auto-send e-mails when any of the monitored data is over or below the expected values.