I cut a pipe cleaner in half, stick it through the bottom hole of a spool of thread, up through the top hole, then put it through the bobbin hole and wrap it over. keeps the bobbin with the same color spool of thread. sometimes I wrap a small pony tail holder around the bobbin (get them in the dollar store, a whole bag for $1).
Then I keep them in the organizer shown earlier:
http://www.joann.com/creative-option...sz=54&start=55