|Milhouse Van Houten (Photo credit: Wikipedia)|
It's barely one letter to go from N.E. Flanders to Ned Flanders. Other characters with street-based names: Milhouse Van Houten, Reverend Lovejoy, Bob Terwilliger aka Sideshow Bob, Kearney the bully, and Mayor Quimby. Mr. Burns' name is an amalgam of Montgomery Park (which used to be the Montgomery Ward offices) and Burnside street. Not mentioned in the article is Homer's half-brother Herb Powell (played by Danny DeVito). He could have been named after Powell boulevard.
Also, for some reason I always assumed that Principal Skinner is named after Skinner's Butte, a hill in Eugene, Oregon, close to the real-life Springfield.
Some other more tentative Portland influences on the Simpsons? The nuclear power plant where Homer works is based on the Trojan Nuclear plant (now closed) near St. Helens. I know that Matt Groening contributed artwork to a campaign mailer that was dedicated to shutting down the Trojan Nuclear plant. And, while many cities had afternoon cartoon shows hosted by clowns or other friendly (yet oddly scary) personalities, I'd venture to guess that Krusty the Klown was inspired by Rusty Nails, who hosted various children's television shows in the Portland, Oregon, television market from 1957 to 1972 - the exact time Groening would have been watching cartoons.