While many of us were consumed by 4th of July festivities, the Seinfeld show that debuted back in the 80's celebrated its 25th anniversary. After airing its first pilot episode back in 1989, on July 5th the show turned 25 years old.
Even though the extremely popular sit-com ended back in 1998, re-runs are still readily available from just about any place on the planet. Jerry, George, Kramer and Elaine (along with a large cast of colorful side characters) are arguably some of the most well known personalities from the era and still maintain a certain level of cultural relevance to this day. As others have mentioned, there aren't many television shows and characters from the era that still airs as regularly as Seinfeld does.
While Seinfeld ended in the late 90's, another popular show known as The Simpsons debuted in 1989 as well. While we all know how culturally significant The Simpsons have remained, other shows from the era haven't been able to stay around in the way that Jerry and Kramer have for so long.
Many of the show's most dedicated fans will likely have already seen it, but the one hour film documenting the show and its beginnings called "Seinfeld: How it Began" can be a great way to reminisce. It goes over how Jerry and then writing partner, Larry David (the person the George Costanza character is based on), began creating and casting the show.
These days Jerry is starring in his own web show called "Comedians in Cars Getting Coffee" where, well, Jerry picks up comedians in various cars and they go for coffee. You can see all the available episodes for free at the show's official website.