The residents of the Maine town of Haven gradually fall under the influence of a mysterious object buried in the woods. (Not an SK connection, but worth mentioning: Peter Straub and his book The Floating Dragon get a shout out in Chapter 10.)
Derry is mentioned and visited several times throughout the book, as it neighbors the town of Haven.
When Jim Gardener comes to on the rocks of the Arcadia resort, he meets young Jack who mentions that his mother was crazy and died in a car crash.
“Where am I?” Gardener asked, and his mind harked back with an eerie totality to the jail cell and the nose-picking deputy. For a moment he was sure the kid would say, Where do you think you are? “Arcadia Beach.” The kid looked half-amused, half-contemptuous. “You must have really hung one on last night, mister.” “Last night, and the night before,” Gardener chanted, his voice a little rusty, a little eerie. “Tommyknockers, Tommyknockers, knocking at the door.” The boy blinked at Gardener in surprise . . . and then delighted him by unexpectedly adding a couplet Gardener had never heard: “Wanna go out, dunno if I can, cause I’m so afraid of the Tommyknocker man.” Gardener grinned ... but the grin turned into a wince of fresh pain. “Where’d you hear that, kid?” “My mom. When I was a baby.” “I heard about the Tommyknockers from my mother too,” Gardener said, “but never that part.” The kid shrugged as if the topic had lost whatever marginal interest it might have had for him. “She used to make all kinds of stuff up.” He appraised Gardener. “Don’t you ache?” “Kid,” Gardener said, leaning forward solemnly, “in the immortal words of Ed Sanders and Tuli Kupferberg, I feel like homemade shit.” “You look like you been drunk a long time.” “Yeah? How would you know?” “My mom. With her it was always funny stuff like the Tommyknockers or too hung-over to talk.” “She give it up?” “Yeah. Car crash,” the kid said.
When Tommy Jacklin travels to Derry, he has a vision of a clown in the sewers.
Tommy had begun to hallucinate; as he drove up Wentworth Street, he thought he saw a clown grinning up at him from an open sewer manhole—a clown with shiny silver dollars for eyes and a clenched white glove filled with balloons.
John Merrill - Ace's grandfather? great uncle? - is mentioned in the description of Ruth McCausland.
Ruth, the only child of John and Holly Merrill, had inherited a fairish sum of money and a fine old house in Haven Village when her father died in 1962.
After a while in Derry alone, half out of his mind with worry for Hilly and David and contempt for what he now saw as cowardice on his part and fear for Ruth McCausland and the others in Haven, Ev had done some drinking at the little bar halfway down Lower Main. In the course of a conversation with the bartender, he heard the story of a fellow named John Smith, who had taught in the nearby town of Cleaves Mills for a while. Smith had been in a coma for years, had awakened with some sort of psychic gift. He went nuts a few years ago—had tried to assassinate a fellow named Stillson, who was a U.S. representative from New Hampshire.
A bit of a stretch (maybe - it doesn't seem like Stephen King does anything by accident), but there's a minor character called Henry Amberson in The Tommyknockers who is one of the casualties of the changes in Haven, when his pacemaker explodes. He might be a reference to Jake's alias in 11/22/63, George Amberson. Perhaps the real George Amberson grew up in Haven with Henry?
“A forest ranger from Newport died,” Dawson said reluctantly. “Who?” “Henry Amberson.” “What? Henry? Christ!” Torgeson felt as if he had been hit hard in the pit of the stomach. He had known Henry Amberson for twenty years—the two of them hadn’t been best friends, nothing like it, but they had played some cribbage together when times were slow, done a little fly-fishing. Their families had taken dinner together. Henry, Jesus, Henry Amberson. And Tierney was in fucking Utah. “Was he in one of the Jeeps they sent out?” “Yeah. He had a pacemaker, you know, and—” “What? What?” Torgeson took a step toward Smokey as if to shake him. “What?” “The guy driving the Jeep apparently radioed in to Three that it exploded in Amberson’s chest.”
References will be here!