Easy way to make a key-value store in a Google Spreadsheet. Just publish as a webapp and use jsonp.

google-spreadsheet-as-database.gs

function doGet(request)
{
  var lock = LockService.getPublicLock();
  lock.waitLock(15000);
  var ss = SpreadsheetApp.openById(request.parameter.id);
  var sheet = ss.getSheetByName('Sheet1');
  var obj;
  var dataRange = sheet.getRange(1, 1, sheet.getLastRow(), sheet.getLastColumn());
  var dataValues = dataRange.getValues();
  if (request.parameter.k && request.parameter.v) {
    var key = request.parameter.k.toString(), value = request.parameter.v.toString();
    for (var i = 1; i < dataValues.length; ++i) {
      if (dataValues[i][0] == key) {
        sheet.getRange (1+i, 2).setValue(value);
        key = null;
      }
    }
    if (key !== null) {
      sheet.appendRow([key, value]);
    }
    obj = {'status':'ok'};
  } else {
    obj = [];
    for (var i = 1; i < dataValues.length; ++i) {
      obj.push ({
        'k': dataValues[i][0],
        'v': dataValues[i][1]
      });
    }
  }
  lock.releaseLock();
  return ContentService
      .createTextOutput(request.parameters.callback+'('+JSON.stringify(obj)+')')
      .setMimeType(ContentService.MimeType.JAVASCRIPT);
}

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// software to the public domain. We make this dedication for the benefit
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// software under copyright law.
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