first of all thanks for the great job - i'm using your datatype a-lot.

just 2 small suggestion:

1. after i create a field i can't edit it. if i want to change the type i need to remove it and than create new one. i think it will be great to edit.

2. in the past i worked a little bit with the php cms expression engine, and they have similar datatype that simply called "Matrix".
    (you can view it here: http://leevigraham.com/cms-customisation/expressionengine/lg-data-matrix/).
    i think this will be great name - short and simple, and very true, because this is actually the purpose of this field - a matrix.
    "repeatable custom content" sounds complex.

thanks and keep on the great job!

Eran.