One problem I've run across a couple of times at work is generating automated PDFs. While reading the Ruby section of Artima, I stumbled across "Creating Printable Documents with Ruby", which cover's Austin Ziegler's PDF library for Ruby, PDF::Writer. Besides having a great API, PDF::Writer also has an extensive manual (generated by PDF::Writer, of course), wrappers for common tasks such as generating tables, reference sheets, and brochures,
I'm wondering how long it'll take before someone writes a PDF target for RI, or, even better, RDoc. In the mean time, I have something that'll give me an excuse to use more Ruby at work.