•An ABC summer musical event expands to three hours this year as the network devotes the night to the CMA Music Festival: Country's Night to Rock (tonight, 8 ET/PT). Among the many artists scheduled to perform are Trace Adkins, Brooks Dunn, Kenny Chesney, Julianne Hough, Lady Antebellum, Martina McBride, Reba McEntire, Brad Paisley, Sugarland, Taylor Swift, and Wynonna and Naomi Judd.

•Ah, what might have been. Gossip Girl (CW, 9 ET/PT) repeats the flashback episode that was designed to be a backdoor pilot for a spinoff that would have starred Brittany Snow as a young Lily. The show was a no-go, but you can still see Snow, along with guest stars Andrew McCarthy and No Doubt.

•Jennifer Beals guests as Cal's ex-wife on one of the better episodes of Lie to Me (Fox, 9 ET/PT). The case involves a fatal fire — and the solution puts a more clever-than-usual twist on Cal's lie-spotting ability. Apparently, the hardest liars to spot are the ones who don't know they're lying.

•Last week, it was Nurse Jackie. This week, another Showtime comedy says goodbye as Weeds (10 ET/PT) exits for the summer.