Give each family member a folder, envelope or index card.  Set aside a little time several times during the week to have each family member sit down and write down a compliment/something to be thankful for each family member and then stick it in that individual's holder.  The individual can check his/her folder as often as he/she wants to see compliments.  You may have to model how to write appropriate "compliments" prior to beginning this activity.

Some examples:

• I was so happy how you did your homework today without asking.
• Thank you mom for cooking my favorite meal today.
• Thank you "brother" for letting me borrow your favorite toy.
• I love how you said such a thoughtful prayer last night.

A modified version for older kids would be to make a Gratitude Calendar.  Print each family member a template of the current month's calendar.  Each day they must write something that they are thankful for.