This should be the last one on Halo Reach...I'm pretty sure!
I've finished the campaign again on Legendary, which was challenging, but a lot of fun. I've found pretty much everything I wanted to find except these...
Datapads are an extension of current PDA technology used by the UNSC to store vast quantities of information that needs to be portable. They don't really play any part in the game, but are rather a hidden object, like skulls and terminals in Halo 3 and payphones in ODST. They tell the story of a mysterious group of AIs acting on Reach. You have to collect all the pads to get the story, but to do that you have to replay the whole thing on Legendary and go rummaging to find them - not something I'm going to do in a hurry!
Instead you can read the transcripts HERE on the Halo Nation Wiki.
As I said that should be it, I'm going to be looking at some stuff I missed in The Force Unleashed II next before replaying Mass Effect 2 so plenty of Video Game stuff to come.