Hey Caper - I like those drawer slides, they are pretty friendly to use and they would have saved me a little more room on the sides, the 1 inch (3/4) wood I use ate up some space on the sides. I have not seen these for sale anywhere near me though which is strange. I just opted for making a box instead. I did however use wood strips to also build up the right side of the cabinet, I just fastened them with toggle bolts, again made it easier to adjust.
One thing I noticed on my pantry is the measurements are all over the place, it's wider in the front and narrows in the back, the wall bows out a bit at the top etc etc... not the easiest closet to work in.
Mrs Evans - I really like that! The pegboard looks pretty neat! it makes the shelves adjustable and you can probably buy other pegboard related hooks and clips to keep items better organized. With that setup mounting a drawer on top of a shelf would be a great idea.
I have seen brackets specifically meant for Kitchen cabinets so you can add a drawer to them