One of my customers, Imagine Easy, is making extensive use of Continuous Testing using Travis CI. Some of the test runs require additional PHP PECL Modules to be compiled and installed, like php-apcu or gearman support. Since Travis provides a new provisioned VM for every test, this happens before every test run, and slows it somewhat significantly down.
While Travis has support for caching similar artifacts between builds for other types of data, it is not yet supported for PHP modules.
So I wrote a small shell script and the accompanying travis setup which copies the modules to a cacheable location after compilation, and tries on start to use those cached modules before compiling it if necessary. A sample setup is to be found at Github.
By the way, Imagine Easy is hiring in New York and Berlin – see some of their job offerings here. I can fully recommend working there, the team and technology is pretty awesome.