How often have you been creating a custom time format and couldn't remember which code does which. Is it 'g' I want, or is it 'H'? Is 'm' for month, or minutes, and is it the long or short form?
Sure, you could follow the link to the PHP manual and look it up there, but why can't the docs be on the same page where you're typing it out?
Date Format Help does just that.
Like this? Check out some of John's other modules:
Short name
date_format_help