The validation app demonstrates every way that the Validation system may be used to good effect.
Here are the contents of the app:
validation/app/
models
user.go # User struct and validation routine.
controllers
app.go # Introduction
sample1.go # Validating simple fields with error messages shown at top of page.
sample2.go # Validating simple fields with error messages shown inline.
sample3.go # Validating a struct with error messages shown inline.