kottke.org posts about Seinfeld
Photographer Richard Prince took photographs of the 57 girlfriends Jerry Seinfeld had on the show and turned it in to the below composite.

See also Jason Salavon's work. (via @sippey)
Update: Max points out I may have misread the article and these 57 girlfriends are not necessarily Jerry's only. Supporting this is Sarah Silverman's inclusion in the composite even though she's was a love interest of Kramer's.
A list of the most New York episodes of Seinfeld.
4. "The Rye" (Season 7, Episode 11)
This episode's titular breadstuff-which Jerry steals from an old lady who refuses to sell it to him, even for 50 bucks-supposedly comes from Schnitzer's, a great New York bakery name if we've ever heard one. The real place was called Royale Kosher Bake Shop. Unfortunately, it's now closed. A Jenny Craig branch stands in its place at 237 W. 72nd St. Also in this episode: Kramer leads Beef-a-Reno-fueled hansom cab rides through Central Park. His skills as a tour guide are questionable, though, as his historical "facts" are impressively inaccurate. For example, Frederick Law Olmsted and Calvert Vaux-not former New York Yankee Joe Pepitone-designed the park.
Already good, Seinfeld got 100 times better when I moved to NYC and got 10 more of the jokes per episode.
If you're anything like me, you take things like 34 People You Probably Didn't Know Were On Seinfeld as a challenge. It's been awhile, but I've seen every episode of that show (most of them at least twice) so I thought this would be easy but I totally had forgotten or didn't realize that Jon Favreau, Catherine Keener, Amanda Peet, Denise Richards, and James Spader were on the show. Guess I'm not the Seinfeld fan I thought I was.
Jerry Seinfeld seemingly wore a different pair of sneakers (mostly Nikes) on his TV show each week...here are 50 pages of analysis of Jerry's shoe choices. For 90s athletic shoe and Seinfeld superfans only. (via @cory_arcangel)
Dozens of scenes from Seinfeld used to explain economic concepts. For instance, in an episode from season five:
George thinks he has been offered a job, but the man offering it to him got interrupted in the middle of the offer, and will be on vacation for the next week. George, unsure whether an offer has actually been extended, decides that his best strategy is to show up. If the job was indeed his, this is the right move. But even if the job is not, he believes that the benefits outweigh the costs.
Economic concepts touched on: cost-benefit analysis, dominant strategy, and game theory. (via what i learned today)
Noted food scientist Harold McGee takes a look at the microbiological consequences of double dipping a chip into a bowl of dip.
Prof. Paul L. Dawson, a food microbiologist, proposed it after he saw a rerun of a 1993 "Seinfeld" show in which George Costanza is confronted at a funeral reception by Timmy, his girlfriend's brother, after dipping the same chip twice.
Patrick Pittman makes a good case for Homicide: Life on the Streets being the best TV show ever. I loved Homicide and am convinced it would have found a great audience in this age of TiVo and quick-to-DVD (it was a difficult show to catch on Friday nights). Re: best TV ever, The Simpsons, Seinfeld, The Sopranos, Six Feet Under, and M*A*S*H have to be near the top of the list...what are your favorites?