One of the cool things I like to do when testing webapps, is to define the testcases using SpecFlow (also known as Cucumber) and then use Selenium to actually execute the testcases against the web-application.

Here is an example testcase:

Feature: SpecFlowAndSelenium
	For demonstration purposes, I want to show how the human-readable
	SpecFlow testcases can be executed using Selenium to operate
	a real webbrowser

Scenario: SeleniumAndSpecFlow
	Given I navigate to 'http://www.google.com'
	Then there must be a control with 'id' 'gbqfq' 
	When I type 'Hello World!' into it
	Then there must be a control with 'id' 'gbqfb'
	When I click on it
	Then there must be a link with 'partialtext' 'Wikipedia' 
	When I click on it
	Then there must be a control with 'id' 'searchInput'
	When I type 'Selenium' into it
	Then there must be a control with 'id' 'searchButton' 
	When I click on it
	Then there must be a link with 'text' 'chemical element'
	And there must be a link with 'text' 'Selenium (software)'
	When I click on it
	Then there must be a link with 'text' 'web browsers'

And here you can see Selenium using Firefox to perform all the actions and checks: