Ruby off the rails
One of the huge benefits of Ruby is the ability to create DSLs very easily. Ruby allows you to create "business rules" in a natural language way that is usually easy enough for a business analyst to use. Many Ruby apps outside of web development exist for this purpose.
I highly recommend Googling "ruby dsl" for some excellent reading, but I would like to leave you with one post in particular. Russ Olsen wrote a two part blog post on DSLs. I saw him give a presentation on DSLs and it was very good. I highly recommend reading these posts.
I also found this excellent presentation on Ruby DSLs by Obie Fernandez. Highly recommended reading!
I use Ruby extensively in my work, and none of it is Rails (or even web) based.
My domain is usually client-side Windows applications (wxRuby GUI) and scripts, automating Excel, Internet Explorer, SQL Server queries and report generation (win32ole COM automation). I also use the sqlite, pdf-writer, and gruff libraries for various data munging and graph generation tasks.
Rails' success has been great for Ruby, but I agree that Rails has received so much attention that Ruby's value beyond the web is often overlooked.
We are mainly a C++ shop, but we've found several areas where Ruby has proven quite useful. Here are a few:
- Code Generation - Built several DSLs to generate C++/Java/C# code from single input files
- Build Support
- scripts to generate Makefiles for unix from Visual Studio Project Files
- scripts for building projects and formatting the output for Cruise Control
- scripts for running our unit tests and formatting the output for Cruise Control
- scripts for manipulating Visual Studio projects and solutions from the command line
- Integration Tests - We can crank out tests much quicker and cleaner using Ruby than C++
- QA's entire testing suite is written in Ruby
Ruby is basically my go to tool for where it makes sense. And it makes sense in a lot of places.
Google Sketchup uses Ruby as an embedded scripting language. You can use it to perform all sorts of 3d modeling and import/export tasks. The scripting works with the free version and there's even decent documentation.