Vulnerable Web Application for Learning

There are various vulnerable web applications out there to hone your skills. Some such packages would include the following:

• Damn Vulnerable Web App – Learn & Practice Web Hacking.
• Vicnum – Lightweight Vulnerable Web Application.
• Web Security Dojo – Training Environment For Web Application Security.
• WackoPicko - Why Johnny Can’t Pentest: An Analysis of Black-box Web Vulnerability Scanners? [PDF]