Can anybody recommend a totally free service for hosting Ruby scripts? It isn't Rails, it isn't even anything too complicated, just a lot of simple ruby scripts?

Heroku.com is undoubtedly the simplest method of getting an easy script online.

If all for you to do is share your ruby scripts (the scripts don't operate on the server but are for sale to others to download and employ), use Rubyforge and/or Rubygems.