The original Reykjavík Roasters on Kárastígur (already on the World66 page) has a sister branch in a converted industrial unit on Brautarholt, a fifteen-minute walk east of the centre. Same coffee — single-origin pour-overs, espresso made with care — but more space, more daylight, and a much better chance of finding a table on a Saturday morning.
A useful stop on the walk out to Klambratún and the Kjarvalsstaðir museum.