CHALKBOARD! 
Mine is a fun green number I picked up at TJ Maxx about 4 years ago.  It resides on the wall of my eat-in dining room amidst some barnyard friends.
 
I change the message on a monthly basis, as you can see this months message is in celebration of spring!

I love when I come downstairs in the morning and find a new message written on it – like this one my daughter wrote for my husband when he returned from a trip to AZ.
 
Special occassions are also marked by this little chalkboard – birthdays, adoption anniversarys, etc.
 
What do you have in your house that you feel everyone should have?