Erik Veenstra's home page - Home of RubyScript2Exe and AllinOneRuby - a stand alone no install version of Ruby, ideal for running from a USB key. I was surprised at how "small" the .exe's generated by Script2Exe were - 700kb on Windows, not bad considering.

Ruby Application Archive - Nice starting point for Ruby based applications or libraries.

Ruby Doc - This is a great site. The search is fanatastic for locating libraries.

Oh yeah and the Ruby Home Page