Take a special card to their grave - or to where their ashes are buried or scattered. You could get this laminated to protect it.
Tie a card or a special message to a helium balloon and let it go up to the sky.
Ask other people for their memories of the person who died and make a book about the person and their 'life story'
Place a message or a letter under some bulbs planted in a pot.
Plant some flowers or a small bush or tree in a place that holds special memories of the person who has died - what was their favourite plant or flower?
Have their favourite meal - Fish and chips? Roast dinner? Curry?
Make a memory box in which to keep things that remind you of the person and some of the special things that you did together – photos, jewellery, reading glasses etc
Make a picture frame for your favourite photographs.
Blow some bubbles and send them your love on the wind