The To-do list is a quest item obtained during the Grim Tales quest. It is obtained by playing the tune written on a music sheet on the piano in the basement of the witch's house in Taverley. Playing the correct tune reveals a secret compartment in the piano which contains a shrinking recipe, the to-do list and 2 shrunk ogleroots.
Transcript
Things to do:
Take out the rubbish
Buy a new record for the gramophone
Check shrunken ogleroot supply
Feed ogleroots to my darlings
Wash the bedsheets
Hang out the washing
Practice the piano
Terrorise the little brat with the ball again
Trim hedges in the garden
Floss warts
Plot revenge on Fritz's murder