One of my biggest frustrations in playing Warhammer 40K is the spread of stats and data across numerous codices, and across multiple pages in each codex.
Here's something that Adrian has done for years, and I finally got sorted for the Lost and the Damned army .. a unified stats sheet.
This is a screen shot of a part of the spreadsheet that I prepared. It means that I have everything I need in order to use the army without that frustrating 'now where did I see that?' rustle of pages in mid game. It is especially important when using an army like L&tD which draws units from multiple codices.
If you play the game every week then by and large this sort of play aid becomes redundant. We don't. It certainly sped up game play last night.