Brett Favre announced his retirement for the third time Tuesday, instantly leading to questions about when he would return.
While the (former?) NFL quarterback may be the current king of unretirement, he's not alone in sports history.
In honor of Favre's latest decision, Yahoo! Sports Blogs looks at seven other classic sports wafflers:
Lance Armstrong — Though it was a big deal at the time, Armstrong's 2009 comeback for the Tour de France will be remembered like Willie Mays' time with the Mets and Joe Namath wearing a Rams uniform. He performed admirably that year, finishing third, but admirable wasn't what he was going for. And though it may have slipped your purview, Armstrong also competed in this year's Tour, finishing 23rd. He says he's done with cycling. This time, we believe him.
Roger Clemens — While with the Yankees, The Rocket announced his retirement early in 2003 and then got a standing ovation by opposing players and fans when he walked off the mound for the final time in that year's World Series. Good thing the Florida Marlins ended up winning that game, or they would have felt mighty silly when Clemens signed with the Houston Astros the following January.
Jay-Z — What is the rapper-turned-mogul doing on a sports list? He's a part-owner of the New Jersey Nets and wrote a song that was endlessly played by the New York Yankees during their 2009 World Series run, so it counts. Jigga's classic "Black Album" was supposed to be his swansong, but he coudn't leave rap alone, the game needed him.
Michael Jordan — Basketball fans like to play the "what if" game in regards to MJ's first retirement. What if he hadn't retired for a year-and-a-half and gone to play baseball? Would the Bulls have won eight straight titles? The proper question might be, what if Jordan hadn't retired? Would he have been able to sustain the drive and desire that made him great? MJ's baseball adventure is part of the story of his career. Asking "what if he hadn't done it" is like asking "what if he hadn't hit that shot over Craig Ehlo?" He did. Let's move on. (We can all agree on one thing, though: nobody plays the "what if" game in regards to Jordan's second un-retirement.)
Urban Meyer — When the two-time national championship-winning football coach stepped down at the University of Florida last December, he did so for about 12 hours. Meyer had resigned due to coaching-related health issues but changed his mind the next day and instead opted for a leave of absence which, as far 
as we can tell, he never took.
Sugar Ray Leonard — By an unofficial count, Sugar Ray retired from boxing a half-dozen times. He's one of the rare athletes to announce his retirement before he turned professional, having declared his intentions to stop boxing after winning a gold medal at the 1976 Olympics. An eye injury forced his first "real" retirement in 1982. That lasted 27 months. (Note: We could have done a top 50 of famous boxing unretirements, but capped the list at one.)
Ricky Williams — Drug suspensions and a lack of interest in football caused the former University of Texas star to retire from the NFL in 2004. A need for money forced his return. He took a year off and studied holistic medicine and played in Canada for one year before going back to the Miami Dolphins in 2007. Since then he has experienced an unexpected resurgence, having one of the best years of his career at 32, an age when most running backs have retired for real.
