Now is a good a time as any to attack your webapp with Badboy:

This release contains many many
new features both large and small. Thanks to your feedback
we have been able gather the requirements from hundreds of users to
determine what to add to Badboy to make it better than ever. The
following major features are brand new in Badboy 1.5:

• Draggable and
  Dockable tool windows
  – arrange the Badboy windows the way you want!
• Unlimited Browser
  Popups
  – Badboy now records and plays back to an unlimited number of popup
  windows!
• HTML Reports
  – Badboy can now save beautiful reports in HTML format
• Timeouts
  – Ensure that your scripts finish on time every time – even when errors
  occur
• Data sources
  – unlimited, customizable data sources!
• Script
  Documentation
  – Add notes in rich text to document how your script is working inside
  Badboy!
• Logging
  Control
  – Better logging controls and log your own custom messages using JScript!
• Server Log File
  Integration 
  – Let Badboy capture and track your log file as your script plays!
• Easy Assertions
  – Just select the text on the page and click a button to create Assertions!
• Spidering – Let Badboy find the bugs for you!
• Popup Message Box Handling – Badboy can now record and playback responses to Popup Message Boxes
• Script Scheduling and Aggregation Run scripts on a schedule you specify, and call other Badboy scripts from each other!