In Zabbix you easily navigate to Latest Data tab and select Values in small combo box and then click „Plain text“. This way you can export 1 metrics at a time. But what if you want to export all metrics for particular host? We are using Postgresql and there isn’t anything easier:

copy (
TIMESTAMP WITH TIME ZONE 'epoch' + v.clock * INTERVAL '1 second' as clock,
from hosts h, items i, history_uint v
where h.hostid = i.hostid
and i.itemid=v.itemid
and like 'slaves%' and clock > 1356080228
) to '/var/tmp/export/slaves.csv' with csv header;