6m MSK144 RX is easy and ideal to monitor in the background whilst dealing with a houseful of people. So far today PSK Reporter Maps shows 10 stations spotted in 7 countries, but at least one more nation has been spotted that was not uploaded.
UPDATE 1450z: 17 stations in 9 countries so far today on 6m MSK144 RX.
UPDATE 2120z: 20 stations in 10 countries on 6m MSK144 RX in last day. The system is still running and will be left on overnight, although I seem to spot most stations in the period between 0600 and 1000z.