KAMAR makes their custom plugins freely available

From the web site

A selection of Plugins designed to enhance the functionality available within FileMaker (Pro, WebDirect, DataAPI and FMSE).

We currently offer three plugins:

  • IDME: FileMaker includes a native function to send emails, however this doesn't allow sending html formatted emails, attachments from a container field and sends a single email per connection. This plugin adds the ability to send bulk, HTML formatted emails (with multiple attachments from file or container field) from within FileMaker over a single connection.
  • IDMP: FileMaker includes the ability to print to PDF (or append to an existing plugin) and limited viewing within an interactive container provided the end user has the correct software installed. This plugin extends this functionality by adding the ability to retrieve a page as an image, merge multiple PDF's into one and even print the PDF document. It also offers performance gains over FileMaker's append to PDF option by keeping the document open all the time.
  • IDMA: A general purpose plugin that adds a range of additional functionality to FileMaker's base function set including arrays, cross file globals, file / folder manipulation, multiple script parameters, command line, fmsadmin commands, and much more.

If you look at the function lists on the website you'll notice that a lot of the functions look like things you can do pretty easily with FileMaker native functions. I've been using the plugins for about nine months now. What they website doesn't talk about is that they are designed to handle large amounts of data quickly. That's why there is so much overlap.