- If you're looking for crazy sci-fi drugs, it seems you can't do much better than Philip K. Dick. Substance D from A Scanner Darkly comes to mind as one that would be interesting to introduce into Shadowrun, in terms of it's effects. The Spice Melange from Dune also seems like something that could be interesting mechanistically - a drug that grants progressive magical power the longer you take it, but you have to keep up with the doses, and it's fantastically expensive...would be an interesting way for rich mundanes to break in on the magic game.
If you want to get really out there, perhaps a new 'Awakened' Drug grants the user the ability to see 3 or 4 seconds into the future for five minutes or so, and then you have some kind of horrible crash afterward, although I imagine the cost for something that potent would be immense.
I dunno. I'm sure someone else will come up with something more exotic soon.