mrs. fittz, they do exist :D
There are 2 types, one that uses full size spools and one that uses bobbins. They are really nice if you don't want to buy 3-4 big cones of a particular thread color, or if you want to use the serger thread in a regular sewing machine but don't have a thread stand. I have 2 of the Bob'n Serge ones.
Here is the full size spool one:
http://www.darrsewnotions.com/darrpage/winder.htm
Here is the bobbin one:
http://www.clotilde.com/detail.html?prod_id=448
There may be more out there, but these are the only ones I know about.