Back in March, well before it was acquired by Google, PostRank released its asynchronous, Ruby-based Web server Goliath.

According to the project page, Goliath is built with the Ruby 1.9 runtime, an EventMachine reactor and this HTTP parser.

PostRank claims that one of Goliath's biggest advantages over other asynchronous servers is: "the fact that by leveraging Ruby fibers introduced in Ruby 1.9+, it can untangle the complicated callback-based code into a format we are all familiar and comfortable with: linear execution, which leads to more maintainable and readable code."

For an explanation of why you might want to use an asynchronous Web server, see our post Wait, What's Node.js Good for Again?.

(Hat tip Mike Loukides)