A Google Script that adds extra powerful functions to my 'scripts' label, e.g. the ability to send emails to Mail Drop for OmniFocus.

n8GmailFilter.gs

/**
 * n8GmailFilter.gs
 * Adds extra powerful functions to my 'scripts' label, e.g.
 * the ability to send emails to Mail Drop for OmniFocus.
 *
 * Details and setup instructions at: http://n8henrie.com/2014/08/using-google-apps-script-to-send-tasks-to-omnifocus/
 */

// CUSTOMIZE THESE VALUES
var myLabelName = 'your gmail label';
var taskEmail = 'your_task_manager@email.com';
var myDebug = false;
// END CUSTOMIZE THESE VALUES

// get the label for given name
var retryCount = 0; 
var success = false; 

while ( !success & retryCount++ <= 10 ){
  try{
    var label = GmailApp.getUserLabelByName(myLabelName);
    success = true; 
  }catch(ex){ 
    Logger.log(ex);
  }
  Utilities.sleep(1000);
}

function bankEmail(messageId) {
    
  var message = GmailApp.getMessageById(messageId);
  var source = message.getRawContent();
  var body = message.getPlainBody();
  
  var myRegex = /Transaction: \r\nAmount of Transaction: (\$\d+\.\d{2})    \r\nDate: ([01]\d\/[0-3]\d\/20\d{2})/;
  
  var matched = myRegex.exec(source)[0]; // The whole match, mostly for debugging
  var amount = myRegex.exec(source)[1]; // The first matched group
  var date = myRegex.exec(source)[2]; // The second matched group
  
  var taskName = 'Transaction: ' + amount + ' on ' + date;
  var taskBody = body;
  
  MailApp.sendEmail(taskEmail, taskName, taskBody);
  
  message.getThread().removeLabel(label);

}

function yourNewFunction(messageId) {
  
  message = GmailApp.getMessageById(messageId);
  
  // do stuff here!
  
}

function processMessage(message) {
 
  var bcc = message.getBcc();
  var cc = message.getCc();
  var body = message.getPlainBody();
  var date = message.getDate();
  var from = message.getFrom();
  var subject = message.getSubject();
  var to = message.getTo();
  var messageId = message.getId();
  var source = message.getRawContent();
  
   if ( to == 'youremail@email.com' 
       && from == 'Your Bank <yourbank@email.com>' 
       && subject == 'Some consistent subject' ) {
     
    bankEmail(messageId);
     
   }
  
  else if ( to == 'youremail@email.com'
           && from == 'Someone Else <someoneelse@email.com>'
           && /search string/i.test(body) ) {
    
    yourNewFunction(messageId);
    
  }
  
  else {
    if (myDebug) {
    Logger.log("\nDarn, didn't match!"); 
    Logger.log('to: ' + to);    
    Logger.log('from: ' + from);    
    Logger.log('subject: ' + subject);    
    Logger.log('bcc: ' + bcc);
    Logger.log('cc: ' + cc);
    Logger.log('date: ' + date);
    Logger.log('messageId: ' + messageId);
    Logger.log('body: ' + body);
    Logger.log('source: ' + source);       
    }
  }
}


function processLabel() {
  
  // Iterate through threads in the given label
  var threads = label.getThreads();  
  for (var i = 0; i < threads.length; i++) {
    
    var messages = threads[i].getMessages();
    
    // Iterate through messages in a thread
    for (var j = 0; j < messages.length; j++) {
      
      var message = messages[j];
      
      processMessage(message);
      
    }
  }
};