At a bare minimum quilt labels should include:
The quilts name (if you gave it a name) or the pattern name
The makers name and completion year
City and/or state of maker
This information is included for posterity sake and should the quilt ever be discovered as an antique in the future this is the information appraisers want.
But rarely is this information included and when it comes down to it... how many of our quilts are heirlooms and do we really expect our quilts to turn up on some future version of "Antiques Roadshow" 100 years from now?
But I am of the mind that quilts are most definitely our form of art and every artist should sign their work in some way.
I try to always label my quilts and I do include this data. If the quilt is a gift I will sometimes put the name of the recipient on the label or the relation (like made especially for my brother XXXX). I really like all of AZ Jane's examples. I also hand embroider most of my labels and like AZ Jane I embroider my signed name in cursive.