I find the MyBrickLink page useful for reminders. I, along with many other sellers
have a shipping method called "hold order open" so that buyers can checkout with
items even though they intend to come back and buy more items in the near future.
I think it would be helpful to show a reminder to all buyers with an order currently
held open by a seller. This could be similar to the entry that shows "stores
with items in my cart". In order to accomplish this, we would either need to
add a checkbox to the shipping methods entries that designates a user's entry
as "held open", or we would need to add a universal shipping option for "hold"
that could be turned on or off by each seller based on their preference.
Taking this one step further, we could have sellers set time flags, such as 7
days. So less than 7 days the link is green, over 7 the link turns orange and
over 14 the link turns red. Or something like that.