FORTUNE — To believe the old saw, you know you’re at the peak of the market when cab drivers start giving stock tips. Well, throw in a new leading indicator — at least for the consumer tech space: pro athletes.  As apps and web properties continue to proliferate in what some people feel is another tech bubble, many former pro athletes are jumping in with their own digital offerings. And many of these websites and applications have only a tangential relationship to watching, or engaging with, pro sporting events. Think of them as sports-related “convenience” tools.  MORE: MLB.com is gearing up for next season  Back in February, former New York Giants running back Tiki Barber launched Thuzio, a company that allows fans to book athletes for an appearance. This summer came the mobile app. At launch, Thuzio raised $1.5 million in funding from RSE Ventures, the firm of Miami Dolphins’ owner Stephen Ross, and has raised $3.5 million to date. The new app, centered on a video feature, makes quick-hit bookings easier: You can hire a current or former pro to have lunch with your corporate board, or to play pickup basketball in the park with your buddies. “The app is an idea that came from some of the events we were doing,” Barber tells Fortune, “where our customers would ask [the athlete], ‘Hey, can you call a friend of mine and say happy birthday?’” A video feature lets athletes record and send a short clip to fans for specific occasions.  The move from playing field to phone is happening with increasing frequency as professional athletes realize that their careers won’t last forever, and that the money may not either.  MORE: The new way athlete endorsements hedge for scandals  “Think about the normal professional progression,” says Barber. “They start young, they’re walking the corporate ladder, they have a couple missteps, and they finally find themselves, by 35, with professional stability. An athlete walks a completely different ladder — makes a ton of money but then retires at 35 and has no professional skill that he can monetize.“  Thus: Hunter Hillenmeyer, a former linebacker for the Chicago Bears, this year launched OverDog, which connects fans with athletes to play videogames. And NBA star Dwyane Wade put out his own fitness app, Dwyane Wade Driven, in June.  Retired outfielder Gabe Kapler and hockey legend Cam Neely are among those who’ve invested in CoachUp, a website founded by Jordan Fliegel. Fliegel was an average high school basketball player until his father hired a private coach, Greg Kristof, who had been the varsity captain at Brandeis. The sessions with Kristof helped Fliegel make his high school varsity team, then varsity at Bowdoin College and ultimately make it to playing pro ball in Israel after graduating.  Fliegel created CoachUp in order to help the many private coaches-for-hire across the country (he estimates there are 500,000 of them, including fitness trainers) manage their business more easily. The site sets up a page for them and handles appointments, allowing them to set pricing packages. Launched in May 2012, it now has 10,000 active coaches in over 60 sports and 75,000 athletes booking sessions with the coaches, Fliegel says. It has raised $2.7 million thus far.  MORE: My apps don’t know me  Kapler got involved, he says, because since retiring, he’s always talking to venture capitalist friends about interesting new tech ideas they’re seeing. “This one really smelled like a winner,” he says. Interestingly, CoachUp also has former Massachusetts senator Scott Brown on board as an advisor (not an investor). “They reached out to me, knowing I had played basketball and had gone through the process of being a college athlete,” Brown, who played at Tufts University, tells Fortune. “When I get involved in things I try to go all in; Jordan knows he can pick up the phone any time, day or night.”  Like CoachUp’s Fliegel, beRecruited.com, a site that lets high school athletes manage their own college sports recruitment process, was founded by a successful college athlete: Ryan Spoon, a former swimmer at Duke University. Spoon founded beRecruited in 2000 and in 2009 acquired Fanvibe, a sports social platform. Vishwas Prabhakara, who cofounded Fanvibe and worked at ESPN as a director of finance and strategy, is now CEO of beRecruited. Prabhakara pulled off something of a relaunch: beRecruited, which is profitable, has 1.5 million registered athletes, and claims to be the largest collegiate recruiting network in the country. “We look at beRecruited as we’re helping student athletes be the best version of themselves they can be,” says Prabhakara. “We’re more of a utility, not a brand like Starbucks. No one knows who we are. If you can figure out the customer acquisition funnel, branding isn’t the most important thing. We’re just trying to provide a valuable service.”  MORE: An app to revolutionize watching the big game?  Many of these ideas seem like natural digital extensions from a life in professional sports. But then again, pro athletes, fairly or unfairly, are somewhat notorious for business failures. (See: Making money after the big contract ends.) And not all of the products coming from retirees are obvious hits at first blush. Mike Wahle, a retired NFL guard who most recently played for the Seahawks, just launched Crowd Cam, a site that culls all of an athlete’s or team’s social media presences — Twitter, Instagram, blog — on one profile page for fans to have an easier time connecting with them, and where “we can address all their value propositions in one place,” he says. (There is also a companion mobile app that allows for recording video.) Thanks to Wahle’s sports connections and influence, more than 75 athletes have committed to using Crowd Cam, but the product doesn’t sound so different from About.me or RebelMouse, other sites that gather different forms of media in one place.  In the end, of course, only a handful of these new digital reincarnations are likely to be champions. But retired athletes shouldn’t be too discouraged about those odds. After all, the same rule applied when they played in the big leagues, too.
Retired big-leaguers are lending their names to a crush of new web sites and mobile apps. But is this game already in the final quarter?