Phenobarbital is still prescribed for epileptic seizures refractory to benzodiazepines, and very rarely, for people with very VERY severe insomnia, and for those users who have been taking barbs long term, from when they were regularly prescribed back in the day, but its not common, and of course there are less and less people around who were alive in those days.
Phenobarb isn't unobtainium, and barbital is used in certain chemistry labs as a PH buffer, its a longer acting barb, but IMHO far more abuseable than pheno, I got some a year or so back, quite a bit of it, and loved it, it didn't love me, but its definately very fun.
Always wanted to try some of the shorter acting barbs, but never had the chance.
Barbs are really dangerous in combination with other sedatives, while benzos bing to the allosteric binding site and increase the effectiveness of GABA, barbiturates bind, and 'lock open' the chloride channels of the GABAa receptor, which is why the lethal dosage does not increase with tolerance to the effects.
Highly addictive too, the barbital did for me, IMO, if your going to get any, of any of the barbs, I wouldn't keep too large a stash around, unless you have the willpower of a saint.