FitNesse.
MarkupCrossReference [add child]
You can add a Cross Reference to another page with the !see statement.

Markup Text
Displayed as
!see .FrontPage See: .FrontPage

Aside from being a nice syntax for cross references, this widget is also used in test suites. If a test suite page refers to test pages with !see statements, then when the suite is executed, the cross referenced tests will be added to the suite.