Hotkey to change some tags on all selected entities in #iD

change_tags.js

context = id;
addTags = { building: 'yes' };
removeTags = ['area','natural','landuse'];

function changeTags() {
    var actions = [],
        entities = _.filter(_.map(context.selectedIDs(), context.entity), 
            function(entity) { return entity.geometry(context.graph()) === 'area'; });

    _.each(entities, function(entity) {
        var newTags =  _.omit(_.merge(_.clone(entity.tags), addTags), removeTags);
        actions.push(iD.actions.ChangeTags(entity.id, newTags));
    });

    if (actions.length) {
        actions.push(t('operations.change_tags.annotation'));
        context.perform.apply(context, actions);
    }
}

myKeybinding = d3.keybinding('changeTags')
    .on(iD.ui.cmd('⌘B'), changeTags);
d3.select(document).call(myKeybinding);

Progress at https://github.com/their/OSM-iD-Browser-Tools. After autofocus it is pretty much down to features "add new area" and "orthogonalize".