Mappping multiple locations

Hi -

I am trying to help my wife with a project for the hospice that she works
for.  She needs to produce a map with the locations of 30 patient addresses
(all in or near our town) marked in some way, like with stars or "pins".
She also needs to be able to update that map almost daily, removing some
addresses and deleting others.

Is there a free service or product online that will allow her to do this,
and which will "store" her list of addresses in between sessions so that she
doesn't have to manually input them every day?

If not a free service or product, then is there a modestly priced service or
product that would do this for her?

Thanks!
Tim