My current favorite tight harmony group is the British trio Coope, Boyes and Simpson. Jim Boyes used to be with Swan Arcade; don't know too much about Barry Coope and Lester Simpson. They have a slew of albums out on the "No Masters" label(as opposed to HMV, I suppose) that feature exquisitely tight, intricate harmonies that vary from traditional to Doo-wop depending on the piece they're singing. My two favorite albums are "Hindsight" (all traditional songs) and "Funny Old World" (mostly GOOD British singer-songwriters). Dick Swain introduced their stuff to my husband and me, and we wish we were three people so's we could sing the way they do!