Who uses playsheets? I do. Who knows what a playsheet actually is? Well, it is simply a piece of paper with the main, most important rules on it. If this is the case, why do I value it so much? The simple fact is, because it speeds gaming up. The playsheets have on them the most important rules - "to hit", and "to wound" charts, armour modifiers, scenarios, exploration charts etc. Admittedly theses examples are for Mordheim, but there are ones for Fantasy and 40k out there as well - they are pretty much the quick charts in the back of the mini 40k rulebook.
I have printed and designed some of my own - or premade ones - for Mordheim and would be lost without them. Upon these plastic, laminated sheets are most of the main rules and post-game actions, which means that there is no need to go hunting through the rule book for the right pages for how much wyrdstone a warband gets etc. I love them, and have expanded my collection to now include the scenarios, the shop list and the skills lists. This is all for ease of use and speed. I have made a number of copies of these, they will be circulated at my gaming group when I'm there so that other players have the same resources available to them as I do.
In all, what I'm saying is... consider it. It works for 40k and Fantasy as well, and generally speeds things up considerably.