I have done the bourbon-soaked oak cube thing.
I also have some Jack Daniels smoking chips, which are chunks from oak JD barrels. I bought them for smoking, but I believe others have reported using them for beer with success.
Since they're already bourbon flavored, I guess you'd steam them to sanitize, rather than soaking in bourbon. (Or you could soak them in cheap vodka if you prefer.)
Bottle conditioning: Robust Porter
Drinking: Saison Dupont clone, tripel
Coming soon: Columbus APA, Rich Red ale