It's a summer of discontent for the live-music business, with major acts shortening their tours or canceling appearances altogether while consumers balk at pricey tickets. But here's one show that won't strain a fan's pocketbook. Sarah McLachlan is playing for free next week at New York's John F. Kennedy International Airport as part of JetBlue's ongoing entertain-the-travelers program. (The catch is you have to be flying the discount airline through its T5 terminal at JFK next Thursday or win tickets through Facebook.) McLachlan has a new record out, Laws of Illusion, and her Lilith Fair festival to promote, so the added exposure couldn't hurt. (Lilith Fair canceled 10 of its planned tour dates because of poor ticket sales.) JetBlue will also hype the singer/songwriter across its marketing channels, including in-flight entertainment and social media. The concert program, via Superfly Marketing Group, started last summer with a dozen emerging bands playing T5. Expect more of these kinds of partnerships, with hip marketers latching onto musical artists for entertainment in unexpected places, and performers looking for credible (preferably media-worthy) ways to be heard.