[MrB]

A few thoughts -

Landscape could be a separate category on its own.
Nature could include wildlife (plants and animals), farm animals, and pets.
Architecture (buildings inside and out + the urban environment) could be a separate category on its own.
People could include portraits, groups, and street photography (human-urban interaction).
I agree that there could be a separate category for any sports.
Technology could include any forms of transport and bridges.

Philip