Beckettian (after Samuel Beckett) has about 26.2k hits on Google.
Homeric.
I mean, it only has 1.3 million Google hits, but it’s still an acceptable term.
There’s “Thoreauvian,” which applies to anyone who owns an acoustic guitar. Similarly, “Shavian” means “not funny.”
I confess: I stole those from an NPR commentary I heard years ago on the exact topic of authors’s names getting adjectated, though I can’t find it in their archives now.
“Authors’s”? Stupid Mac keyboard.
Why not? Tarantino was mentioned earlier; so film directors would seem to be fair game.
Thus my contribution: Capraesque, for a film with a hero overcoming adversity, and having a happy ending.
Gibsonian has 31,700 google hits, and I believe William Gibson is still among us.
Goes back to lurking.
How about Mosaic?
Of those suggested, I have personally used Dickensian, Shakespearean, and Orwellian.
I tried to suggest the usage of “Algerian” as an adjective form of Horatio Alger, but someone said it was already taken.
Oh, I’ve heard Joycean plenty. The NYTBR had a brief love affair with the word, back in the early 90s, I think.
I used to hear Dantean a lot in school.
Bad writing on my part – I was saying “Fitzgerald, no” – period. Then the next two are a new sentence, both forms I have heard.
Damn, where’s an editor when you need one?
‘Intelligent Designean’ doesn’t roll off the tongue quite as easily as does ‘Darwinian’, eh?
Although he’s no author, might I suggest a new adjective: Cruisean, to be used when the object is leaping about as though possessed by evil spirits-Google Cruise+Oprah. 
I’ve heard “Seussian” used.
Any women?
I like “Heinlein-esque”, which gets 1,760 hits.
“Whedon-esque” gets exactly 516,000 hits (this is a TV producer, sure, but he also does a lot of scriptwriting, if that is allowed here). Of course, it does appear to be the domain name of at least two websites, so I’m not sure how that is effecting the results.
In honor of the Dune thread currently rolling about, I searched for “Herbert-esque”, getting 293 results.
“Mosesish” gets 4 results, two of them from a conversation in a message board, “Moses-ish” gets 146 results, thanks to the addition of the prodigal dash, and “Moses-esque” gets 318 results. Most of these examples (or rather, the 4 or 5 Google hits that I glanced at the summaries for) seem to be used to mean “preachy”. I’m not sure if Moses counts as an author (the way I understand it, if he did author the stuff he’s credited with, he would have had to have dictated it, since he didn’t speak the language they were written in), but I couldn’t help myself. 
A word for the creator of Harry Potter’s flair for neologisms, character names and wordplay might be described as… Rowlinguistic. (Yeah, I just coined that. >>Puffs chest. <<)
Hitchcock was primarily a screenwriting contributer and screenplay adapter. His forte was really in his innovative directing. He has no writing credits during the 50s, 60s and 70s.
So Tarantino-esque could easily allude to his scripts, plots, dialogue and direction, but Hitchcockian would almost never refer to Alfred’s scripts.
I thought I was coining “Rowlinguistic” but somebody beat me to it. Grrr.
23,500 hits for Nabokovian. There’s even a bloody publication called The Nabokovian. And I’m surprised it’s taken this long for his name to pop up in this thread; this guy’s a fricking god.
I dunno, I think “Rowlingtastic” sounds better
Randian.
Damn, I guess Lacanian doesn’t count then, since that doesn’t really describe Lacan’s writing style but his ideas.
There’re Spencerian sonnets. abab bcbc cdcd ee So incredily hard to write.
Wintersonian, referring to Jeanette Winterson’s writing, usually regarding the attitudes toward sexuality. I do believe Winterson is only in her forties or fifties, and has emerged quite recently as a writer – she published her first book in 1985.
Morrisonian, referring to Toni Morrison. It’s generally used to describe the writing of other so-called women’s writers.
Fanonian, used to describe writing that shows views on race (especially in regard to intellectualism) similar to Frantz Fanon’s. I guess that’s like Lacanian
Dickinsonian/Dickensonian* to describe poetry like Emily Dickinson’s. You know – “The yellow rose of Texas is the sweetest girl I know” vs. “He ate and drank the precious Words – / His Spirit grew robust – / He knew no more that he was poor, / Nor that his frame was Dust – . . .”
Adjectivization of authors’ names is incredibly common in critical writing, so the list could be infinite.
[small]*I googled both spellings, and both seemed acceptable. The OED-online is reluctant to load on my computer, so I can’t offer anything more definitive than that.[/small]
Plathetic.
Jonglish.
Ninny.