No Ruby shelf is complete without a copy of the Pickaxe book. For many, this was their introduction to Ruby. There are free versions of the first edition available free (and legally) online here, but they're terribly out of date. This newest edition is updated to cover Ruby 1.9, one of the first major Ruby titles to do so.
Webgen is a static web page generator. Instead of Ruby code running on the server to generate web pages, the developer runs these scripts to generate static HTML pages. This is great for a simple web site, and will work on any web host. Version 0.5.8 improves Ruby 1.9 support, only one gem dependency (feedtools) needs updating. There was also a webgen command-line tool added, as well as numerous other improvements.
HighLine 1.5.1 Released
HighLine aims to remove the tedium and error-prone process of using gets and puts for input and output. This includes tools to make input validation and error checking easy. Version 1.5.1 makes HighLine fully Ruby 1.9 compatible.