After a few slow years, HBO is worth paying for again. There was the outstanding WWII miniseries “The Pacific,” the slowly unfolding and captivating “Treme,” the upcoming seasons of “True Blood,” “Hung” and “Entourage,” and at least one more season of “Curb Your Enthusiasm.” But the one that has me most excited is “Boardwalk Empire,” the new series produced by Martin Scorsese and starring the ever-awesome Steve Buscemi. The period drama is set in Prohibition-era Atlantic City, and looks like it delivers a “Sopranos”/”Deadwood” level of sex, violence and general mayhem. Yes, this will be a show for grownups only. It debuts in the fall, but here’s a couple of trailers to get a taste of what’s to come. Gotta love Buscemi dressed like Gatsby.