The Internet is jammed with more than a billion websites to choose from, but only a fraction of them are useful. Among the most productive are 10minutemail.com, which gives you a temporary throw-away email address that expires in 10 minutes. This is especially useful on sites that require email validation for any purpose. Another amazing website is virustotal.com, a free service using more than 60 security scanners to detect viruses and malware. Tech Gumbo has done the heavy lifting and gives us its choices for the most useful websites.