Had a mad idea for a challenge whilst planning a trip to London. How about a legacy-style challenge where all the household members have to be named after Underground stations? You could potentially do it with other subways too.
Spouses would be renamed upon marriage. As a bonus, you could even try to do the challenge one line/route at a time, and change the Sim's clothes and/or hair colours to match that route's colour on the map. Longer station names could be abbreviated, and for one-word stations, you add "Station" as a generic surname.
Example:
Male founder named Mornington Crescent.
Marries Eliza Pancakes who is renamed Camden Town.
Children: Tower Hill, James Park, Bank Station.