With SiriOus installed in your iOs device you can do almost similar things as if it's a real Siri. This tweak can be found in Cydia, under this URL source: http://apt.if0rce.com/.
So what ever your activity you used to do by your fingers can now be replaced by your voice. Is not that great? But be ware that this tweak may add more problem to your iPhone's battery life based on some people have reported.
You can watch the video SiriOus is demoed:
Well Siri0us does not 100% correct in writing the words dictated by the man, this is understandable. Even Siri needs a technique dictation to get the satisfying result, read this: How To Improve Siri Dictation On iPhone 4s (Video).