Howard Stern is already promoting new artists in advance of his debut as the latest “America’s Got Talent” judge. After singer-songwriter Geron Hoy asked the shock jock on Twitter to take a listen to his tune “Lunatic,” Stern unexpectedly re-tweeted a link to the song to his more than 1.1 million followers. Hoy says the resulting interest made his Web site crash. Hoy told Lisa G, a reporter on “Howard 100 News,” “He’s given me the confidence to keep going.”