That came up the other day and the Fremch Republican Calendar was cool as fuck, in particular the system for naming each day of the year:

The Catholic Church used a calendar of saints, which named each day of the year after an associated saint. To reduce the influence of the Church, Fabre d'Églantine introduced a Rural Calendar in which each day of the year had a unique name associated with the rural economy, stated to correspond to the time of year. Every décadi (ending in 0) was named after an agricultural tool. Each quintidi (ending in 5) was named for a common animal. The rest of the days were named for "grain, pasture, trees, roots, flowers, fruits" and other plants, except for the first month of winter, Nivôse, during which the rest of the days were named after minerals.