READERS' PICK: So, you've just discovered early British punk, but you don't know where to turn after buying Never Mind the Bollocks Here's the Sex Pistols and The Clash. Or, you're digging German prog rock, but after Can and Neu!, what else is there? Your safest, cheapest and most educational option in these matters is to tune into Kidd Squidd's Mystery Jukebox. Airing Saturday afternoons--every one!--from 2 to 4 p.m., on every thinking person's favorite radio station--community radio 91.3 KXCI-FM--the estimable Mr. Squidd (the cat's real name is Dave Squires) gives you a righteous tutorial on the aforementioned periods of musical history and just about any period you can dream up. In a world where DJs have become "on-air personalities" and "talent." the Squiddman is merely a well-informed music geek with a radio show. Is there anything better?