Say you, say me, SASE
Do you want to know entirely too much about the magazines you send your poems to? You're in luck! Duotrope's Digest, "an award-winning, free (sort of) writer's resource listing over 3400 current Fiction and Poetry publications" gathers data from writers on everything from response times to acceptance rates to whether or not a certain magazine will write you a nice little note with your rejection. One example from their "Top 25 Lists" lists the best and worst response times as "The Slothful" (for shame, Coconut) to "The Swift" (keep up the good work, Eunoia Review!)
Gone are the days of thumbing through The Poet's Market in the corner of the bookstore and maybe slipping a recent draft of "The 7-11 Rants" into the crease on page 458.
The staff at Duotrope's Digest handle the guideline updates and listings, but the information for response times, et al. is culled from writers who have enough time to catalog such not-really-different-than-it-ever-has-been information. Time, one imagines, that could be used volunteering to read for any of the many often understaffed magazines out there. Or, at least, time that could be spent at The Library of Congress's National Jukebox, where one can wile away the hours listening to free historical sound recordings while typing up that "it's been six months and still no response" query letter.