The mail-gpg gem is a plug and play solution for sending and receiving GPG encrypted / signed email in Ruby. Also included is an extension to ActionMailer for even more ease of use in the context of the Rails framework. My work on mail-gpg is sponsored by Planio, where we use it to provide highly secure email communication for our customers.
Filling out PDF forms is no pain anymore if you use pdf-forms, which abstracts away all the gritty details of FDF file creation and PDFTK wrangling.
Acts_as_ferret is a fulltext search plugin for the Ruby on Rails framework. It was very popular during the early days of Rails but later I sort of had to give up on it because of stability problems with the underlying Ferret C library in combination with newer Ruby versions. The good news is that thanks to fixes from various contributors and the very recent work of Dave Balmain, Ferret’s original creator, Ferret now passes all tests again on the latest MRI Ruby (2.2.2 at this writing). Yay! I might do some work in that area again soon…