This is a pretty simple instructable on how to reuse pill lids. Normally you tear the label off and put some words on the lid. Unfortunately, the lids are typically made out of polypropylene, which is horrible at accepting any kind of "permanent marker" markings. They wear off easily.
To get around this, sand the lid with rough grid sandpaper (80 grit), write, and then fire-polish the lid to bake it in.