I don't partake, and it's slightly cringey when the top YouTube keeps recommending videos posted by "The Bong Druid Of Mammoth Weed Mountain" and "The Stoned Meadow of Doom"....the frankly embarrassing dope culture surrounding the sludgier side of metal, all these bands called Bong Goblin, Sativa Drang, Stoner Muffin' and that sort of thing, either come across as incredibly old fashioned or incredibly immature...
BUT on the other hand, I like me some utterly unashamedly backward-looking heavy pentatonic Sabbath-worship. Big grunty riffs with bare-controlled feedback. Bonus points for female vocalists, and if they manage to do something around a concept (horror, sci-fi, whatever) without it being cheesy.
A few bits and bobs that I've been listening to recently:
Kröwnn
Songs about Conan the Barbarian? Umlauts? Big heavy riffs? Wizards+Dragons+Swords artwork. How utterly ridiculous. And yet I've been listening to it a lot, and after all the riffing, they sneak in an atmospheric harp-and-oboe outro.
Blood Ceremony
Flute solos! Female vocals! Completely redolent of Heep, Tull, Sabbath and that whole period, but jolly good fun, and my nagging thought is that if they didn't exist, someone would have to invent them.
Holy Grove
Heavy fuzz riffs. More female vocals. I found a few records by the Italian record label "Heavy Psych Sounds" in a record shop in Florence, and it turns out the label is entirely appropriately named.
Devil Electric
Even more pentatonic riffage and ferocious female vocals, this time from Australia.
Vakunoht
Now-defunct local band obsessed with the golden age of Soviet space exploration. I saw them many times in the now-defunct Captain's Rest basement. Lovely chaps, fantastic live, and the proggy-riffy-psychey lunacy of their only album pretty much sums them up.
I've skipped over a few of the more obvious/classic examples of the genre (yer Electric Wizards and Sleeps and all that) but I'm keen for other recommendations if anyone has any.