Kaphotics and Omegadonut created it. Kaphotics actually came up with several useful RNG Related Codes, but I mainly use the MTIVRNG code.
Here's how it works. Go to your badge screen. Press Select (do NOT press select ANYWHERE ELSE). Then press the little button in the bottom Left Hand Corner to look at your trainer card. Your money will have changed to a new number, write that down, then flip your trainer card over and you'll notice that your ID has changed too, write that down.
These two numbers will make up your MTIVRNG, and you can use them to predict the IVs of the next monster you encounter (stationary, wild, sweet scented, fossil, gift, roamer, etc) and the next egg you get. Omegadonut has a post on how to do that here. Monster IVs will be (typically) frames 1-6 (roamers are slightly different) and eggs will be 8-13.