ChordSheet.com is an easy to use online tool to create PDF files of song chord progressions.
You can use it right away but registration is recommended to keep your work permanently.
And it is free anyway.
It is by no means a "real" layout or professional music notation software.
But you can create simple chord charts really fast and efficiently.
It is not a WYSIWYG editor but uses a simple plain text format.
So you can use copy+paste to rearrange quickly.
ChordSheet.com is intended for "chords only" sheets, so adding lyrics is not supported.
Or if you need to write down melody and rhythm as well, you are better off with a real music notation software.
Write down the chord progressions of your students favourite songs.
Make chord sheets for your band mates.
Whether it's your own songs or covers.
As a cheat sheet. Just in case.
Examining songs is a very good exercise to improve your own songwriting skills.
And the best way to examine a song is to write down the form or arrangement yourself.
You can find detailed information in the how-to section.