By far, the two most interesting, insightful voices on Southern California commercial-free radio belong to Mike Kaspar and Nathan Callahan on Weekly Signals, broadcast on KUCI-FM 88.9 every Tuesday from 8 to 9 a.m. The show, celebrating its 10th anniversary this year, features Kaspar and Callahan discussing current events with a witty flair. But don't think it's lightweight babble. No other radio show in the state has a better list of on-air guests: Seymour Hersh, Vincent Bugliosi, Steven Pinker, Daniel Ellsberg, Garrison Keillor, Paul Krugman, Robert B. Reich, Errol Morris, Joseph Wilson, Anne Lamott, George McGovern, Joe Klein, Arianna Huffington, Barbara Ehrenreich, Karen Finley and Sidney Blumenthal. KUCI's broadcast strength is a tad weaker than smoke signals, but you can also listen to their show at the station's website or the show's podcasts.