A clever alternative to the Post-It note, from European company Manufactum. I'd install this stainless steel roll holder (21.50 EUR) right next to the telephone:

Below: In an anti-Blackberry moment, I would also order the Zeuss Italian address index system from Manufactum (107.80 EUR), which holds up to 600 index cards and requires no new technology skills (and is also far more stylish than its US counterpart, the Rolodex):