Above are printable chord charts for C6 (GCEA) and G6 (DGBE) tunings, of the chords you can use in their respective keys. This can act as a handy reference guide if you want to write your own songs or figure out the chords to a song you don't have the chords for.
If you would like to purchase a laminated copy, they are available from Mark at Bytown Instruments.
The PDF document above, from Howlin' Hobbit, has six different chord progressions, each in seven keys, diagrammed for GCEA tuned ukulele. They may help you if you want to write your own songs or figure out the chords to songs you hear but don't have the chords for.