pick up trash or do a service, plant a tree or flowers, butterfly release,
floating lanterns (those last two are great with kids), do something physically challenging (hike the Grand Canyon, run a marathon, etc.), pay for someone's meal anonymously, learn a song on an instrument, invite those close the individual over for dinner/ice cream/pool party, etc.
I found it extremely beneficial and healing for me to have something to do, some where to channel the love I wasn't able to share anymore when my daughter died.