Watir. Automated testing that doesn’t hurt

Watir, pronounced water, is an open-source (BSD) library for automating web browsers. It allows you to write tests that are easy to read and maintain. It is simple and flexible.
Watir drives browsers the same way people do. It clicks links, fills in forms, presses buttons. Watir also checks results, such as whether expected text appears on the page.
Watir is a family of Ruby libraries but it supports your app no matter what technology it is developed in. They support Internet Explorer on Windows, Firefox on Windows, Mac and Linux, Safari on Mac, Chrome on Windows and Flash testing with Firefox.
Like other programming languages, Ruby gives you the power to connect to databases, read data files and spreadsheets, export XML, and structure your code as reusable libraries. Unlike other programming languages, Ruby is concise and often a joy to read.

http://watir.com/