In this WordPress plugin project we were asked to adapt an existing plugin titled Subscribe and Download. This is a plugin that sites can use to build an email list by requiring the user to submit their email address to access a file for download. This is a popular system of restricting access to premium content in return for contact information.
Our customer wanted to be able to collect business names and phone numbers in addition to the standard name and email combinations. These fields needed to be validated, processed and passed via the MailChimp api to custom merge fields in MailChimp.
Because the Subscribe and Download plugin did not have action hooks or filters we could use to enhance it we had to resort to hacking the plugin and creating a custom version for our client. We did this and tested the plugin, finding it fully functional in passing data to the MailChimp merge fields from the added form fields.
If your WordPress site needs functionality similar to this let us know. We can provide either the Subscribe and Download plugin or another solution.