Some airline route maps, showing the routes flown by each airline.
British Airways, whose flights remind me a bit of a daddy long legs. None of these maps show code shares, where you book with one airline, but are flown by a collaborator. BA’s network is actually more complete than shown, but the red routes are those where BA ‘flies the flag’.
American airlines. Lots of flights within the Americas, unsurprisingly. Not many options for flying to Cuba though!
A collection of regional airlines:
Dark red: Alaska Airlines; blue: Aerolineas Argentinas; green: Easyjet (should probably have been orange!); light red: Air Madagascar; purple: Iran Air; orange: Air Koryo (the North Korean flag carrier); black (all black?): Air New Zealand
Purple: LAN Airlines (Chilean); green: South African Airways
Flight data from openflights.org (modified), using the Robinson projection.