In more and more cities, street furniture or devices have been popping up in the last years that are intended to make it more comfortable for cyclists to wait esp. at traffic lights. After several discussions on various channels (also recently here in the forum), there is now a proposal on how to tag these devices. The proposal suggests cycleway=waiting_aid on a node on the cycleway, and additional subtags to specify different shapes and properties.
See the proposal page: Proposal:Cycleway=waiting aid - OpenStreetMap Wiki
Please discuss this proposal on its Wiki Talk page.