My kneeboard contains a clean sheet of A5 underneath the plastic outer cover for ATIS, clearances etc; clipped on top would usually be my plog. A stopwatch is clipped to the top right hole. Inside you'd find a RNP (very useful for in flight div work), RT freq reference cards for north/south VFR charts (because I couldn't work out what to do with them, so slid them in and forgot about them), copies of the VFR plates (Pooleys guide) for my planned airfield with a china graph arrow drawn on the plastic pocket as to which direction I plan to arrive from; there are also copies of planned div plates too. There are 2 sick bags, and a laminated pax brief reminder. The chart will either sit on my lap, or on the back seat with the headset bag containing a torch and my log book.
Finally if flying a lengthy trip (or going abroard) I'll take my entire flight case containing much crap amongst all sorts of useful contraptions from a yoke clip (if planning to fly an inst app) to a headset attachable lamp, blanks, note pads, (foggles bizarrely!!). Also in there are inst plate booklets for most of the UK, licence, and medical.
Who needs a memory?!