Pictured is a sampling of the best I've got (see larger image). Clockwise from top left:

• Cassius Marcellus Clay - March 22, 1963 — His mama named him Clay; I'm gonna call him Clay. (Anyone know what movie that line is from?) Speaking of Clay's gold medal at the 1960 Olympics in Rome, TIME wrote: "In the Olympic Village he swarmed over foreign athletes, yelling 'Say cheese!' while he snapped photos, swapped team badges, and winked at pretty girls. They loved him. If there had been an election, he would have won in a walk."

• Hugh Hefner - March 3, 1967 — An artsy cover depicts a wood sculpture by Marisol, whose work appeared on several TIME covers. Excerpt from the cover story: "He took the old-fashioned, shame-thumbed girlie magazine, stripped off the plain wrapper, added gloss, class and culture. It proved to be a surefire formula, which more sophisticated and experienced competitors somehow had never dared contemplate."

• Man on the Moon - July 25, 1969 — "A Giant Leap for Mankind" is the headline of the cover story on one of the most fascinating events in modern history. Publisher James R. Shepley's letter reads, "Although TIME ordinarily closes on Saturday evening, we felt compelled to hold the magazine open until Monday, in order to report the climax of man's first attempt to walk on the moon." (Neil Armstrong climaxed as he walked the moon? Gross!) Shepley also credits then-associate editor Leon Jaroff, who still writes columns for TIME.com.

• Reggie Jackson - June 3, 1974 — Among the strangest oddities in TIME's history is that the Oakland A's made the magazine's cover four times in the early 1970s, while Elvis Presley never appeared at all. Publisher Ralph P. Davidson's letter relays an anecdote from an interview with A's owner Charles O. Finley: "When asked about his somewhat strained relationship with Jackson, Finley responded with a string of obscenities informing [writer Philip] Taubman: 'If you had a brain in you, you'd be an idiot.'"

• John F. Kennedy - Nov. 7, 1960 — "Candidate Kennedy" the cover calls him, just days before he defeated Richard M. Nixon, the man who gave his "last press conference" following a failed 1962 bid for California governor, stating, "You won't have Dick Nixon to kick around any more." Alas, he would return, and Alex P. Keaton had himself a hero.

• John Lennon - December 22, 1980 — Publisher John A. Meyers' letter delivers this quote from Christopher Porterfield, who covered the Beatles' 1964 American invasion and, yep, is still at the magazine in 2004: "Of all the Beatles, Lennon was the one who showed the greatest depth and complexity. His was the growth I expected the most from, and now that growth has been cut short."

• Jimmy Brown - Nov. 26, 1965 — In his final season, Brown scored 21 touchdowns and amassed nearly 2,000 yards from scrimmage in a 14-game season at age 29. In Dick Schaap's autobiography, Flashing Before My Eyes," there is a chapter (8) titled "How I Stopped Jim Brown." Schaap, a goalie for the Colgate lacrosse team in 1955, recounts how three of his 22 saves against Syracuse came on shots by Brown that he never saw. Brown put four past him, including the game-winner in overtime. Schaap remembers Brown as "the best lacrosse player who ever lived."