1. Chemical labeler: The drug system is friggin awesome, allow the production of so many different qualities and variations of each base drug, but what happens when you lump a bunch of different qualities of the same drug together? Only those with the proper knowledge have any clue what is what. Your average street dealer isn't gonna have insane knowledge of chemistry, but he still needs to be able to tell the difference between the various qualities he's selling. Thus, a chemical labeler, which appends a short tag to the chem in quesition, V-202 becomes Street-grade V-202 or Crimson Moon V-202. This would e left up to the discretion of the person labeling them, so they can still attempt to base of shitty chems as "the good stuff".
2. Smokables and smell: We have the smell code in game, allowing for the use of various fragrances, but it'd be cool to see chummers who smoke a lot of weed or cigarettes to smell like it, at least if they don't cover it up.
3. Mixing of drugs: Into drinks, either for the fun of it or more sneaky like to mess with your enemy. New drink, the mixloko, take a Silk, add your chem of choice and enjoy. Also, lacing joints with various other drugs to get different effects.
All I can think of for now? Thoughts, opinions, additions?