A memorial is something designed to preserve the memory of a person, event, etc, as a monument or a holiday.
For funeral homes and related services
Funeral homes deal with all things that has to do with the burial of loved ones and keeping the memory of such loved person alive. Using a .MEMORIAL domain for your funeral home service make it clear that you really mean business when it comes to keeping the memories of a dead loved one alive.
For sculptor and wood carver
Monuments and statues are raised in honor or memory of heroes and really important people. As a sculptor you are charges with keeping the memory of things alive in stones and wood. Since this is the internet age, using a .MEMORIAL domain name for your website will only show that you really do care about keeping memories alive.
For museum website
A museum is a place where memories of past events are kept. Using a .MEMORIAL domain name for your museum webpage will only make your museum more unique.
For photographers and graphics artists
A picture they say is worth a thousand words so also is a painting. A picture or painting is a tool to keep the memory of a particular event or look forever alive. Show that you really grasp this concept by registering a .MEMORIAL for your website will gain your more clients.