Sample Item Status relationship model

class LibraryItem(models.Model):
    owner = models.ForeignKey(Member)

class Status(models.Model):
    name = models.CharField(max_length=50)
    
class ItemStatus(models.Model):
    item = models.ForeignKey(LibraryItem)
    status = models.ForeignKey(Status)

# Somewhere in the app at startup you initialize all the statuses:

all_statuses = ('I own this', "I've read this", "I've played this")
book_statuses = (all_statuses[0], all_statuses[1])
game_statuses = (all_statuses[0], all_statuses[2])

allowed_in_book = []

for status in all_statuses:
    s = Status(status)
    s.save()

for status in book_statuses:
    s = Status.objects.get(name=status)
    allowed_in_book.append(s)

# Now allowed_in_book is the list of status objects that we use to pull
# the dropdown lists from and check before saving

# Each time the user updates a status, you add or delete an ItemStatus object

# To extend this to 'reading (with current page stored as well)' or
# similar model-specific objects, I would just create another model object 
# in the same way:

class ReadingCurrentPage(models.Model):
    status = models.ForeignKey(ItemStatus)
    current_page = models.IntegerField()

# However, if you are really really expecting zillions of users, highly
# normalized schemas like this don't scale well.  The best thing in that
# case is to be really ugly, and go back to your original model, but just
# keep extending it:

own = models.BooleanField(default=False, db_index=True)
used = models.BooleanField(default=False, db_index=True)
current = models.BooleanField(default=False, db_index=True)
want = models.BooleanField(default=False, db_index=True)
watching = models.BooleanField(default=False, db_index=True)
top = models.BooleanField(default=False, db_index=True)
seen_in_theaters = models.BooleanField(default=False, db_index=True)
# achievements_unlocked, Actually get this from the XBL API!

# I wouldn't really suggest it though -- you'd have to be getting
# Facebook-level hits to make it worth the maintability headaches