One of the great strengths of the WordPress universe is its plethora of plugins (say that 10x fast). But every now and then you’ll find you need WordPress to do something that no plugin can do. This might be interfacing with one of your legacy systems, or performing a very customized calculation, or even just doing something an existing plugin does, but slightly differently.
In rare cases like this it can become necessary to get a custom WordPress plugin built for you (or switch to another platform besides WordPress). Custom plugins require knowledge of how the WordPress core is built and also the full range of WordPress web programming languages (PHP, MySQL, HTML, CSS, JavaScript, Jquery).
Oftentimes, there are alternatives that may be easier and/or cheaper than going the custom plugin route. Crunch42 has built several custom WordPress plugins for specialized needs, and is happy to discuss your needs with you.