S - K - Siwa
Map shows travel times to nearest market (Lidl, Valintatalo, S-Market, Prisma, Alepa, Sale, Citymarket, K-Market, K-Supermarket, Siwa) using public transport at 16:00 in Monday afternoon. First sector (red one) is <5min, white lines are in 5 minutes intervals. Map is missing some markets, most significant everything in Kauniainen.
Idea came from Great Britain travel times. See also Janne Aukia's version (in Finnish): map with central point in Helsinki centrum.