Simple IMPORTJSON function for Google Sheets.

importjson.gs

/**
 * Import data from a remote JSON document.
 * 
 * @param {url} URL of the JSON document
 * @param {path} dot notation path to the value you want to extract
 *
 * @return a single value extracted from the JSON.
 *
 * @customfunction
 */
function IMPORTJSON(url, path) {
  Logger.log(url);
  
  var cache = CacheService.getDocumentCache();
  
  var data = cache.get(url);
  
  if (!data) {
    var response = UrlFetchApp.fetch(url);
    
    if (response.getResponseCode() == 200) {
      data = response.getContentText();
      cache.put(url, data);
    } else {
      data = "null";
    }
  }
  
  data = JSON.parse(data);
  
  if (!data) {
    return "";
  }
  
  path = path.split(".");
  
  for (var i = 0, key = path[i], l = path.length; i < l; i++, key = path[i]) {
    data = data[key];
  }
  
  return data;
}