Our friends at CodeDay.org have open-sourced the PHP library they wrote to integrate their electronic signatures requirements with Legalesign.
CodeDay have deployed e-sign waivers using Legalesign for their event at Philadelphia. We're a huge supporter of CodeDay, they set up great opportunities for people of all stripes, who may never usually have the chance, to innovate and code new apps and games, and have a lot of fun doing it.
They've been kind enough to open source the PHP they wrote to integrate with Legalesign, and what a great job they have done. Elegantly coded and beautifully documented, check it out at https://github.com/tylermenezes/Legalesign-PHP. Happy coding!