Google Spreadsheet/Apps Script custom function for getting Klout scores for Twitter screen name(s). You can File > Make a copy of this template https://docs.google.com/spreadsheet/ccc?key=0AqGkLMU9sHmLdDVzZWdLbElhM3NYM2VQZi1lYjZXUUE&usp=drive_web#gid=0 for working version of the code

gistfile1.js

/*  Copyright 2012  Martin Hawksey  (email : [email protected])

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

function getKloutScores(screen_names,klout_apikey){
  var output = [];
  for (i in screen_names){
    if (screen_names[i][0]!=""){
      output.push([getKloutScore(screen_names[i][0],klout_apikey)]);
    }
  }
  return output;
}

function getKloutScore(screen_name,klout_apikey){
  var cache = CacheService.getPrivateCache(); // using Cache service to prevent too many urlfetch 
  var cached = cache.get(screen_name);
  if (cached != null) { // if value in cache return it
    return parseFloat(cached);
  }
  try {
    var options =
    {
      "method" : "get",
      "contentType" : "application/json"
    };
    var response = UrlFetchApp.fetch("http://api.klout.com/v2/identity.json/twitter?screenName="+screen_name+"&key="+klout_apikey, options);
    var id = Utilities.jsonParse(response.getContentText()).id;
    if (id){
      Utilities.sleep(500);
      var response = UrlFetchApp.fetch("http://api.klout.com/v2/user.json/"+id+"/score?key="+klout_apikey, options);
      var data = Utilities.jsonParse(response.getContentText()).score;
      cache.put(screen_name, data, 604800); // 604800 = cache set for 7 days
      return data;
    }
  } catch(e){
    Logger.log(e);
  }
}