Some good links:

• http://www.yahoo.com.
• http://www.yahoo.com again.
• brokenlink.html: this page.
• brokenlink.html: this page again.

Some bad links

• http://dcm.uhcl.edu/badlink1: an invalid link.
• http://dcm.uhcl.edu/badlink1: the invalid link again.
• http://dcm.uhcl.edu/badlink2: another invalid link.