Libana is a world music ensemble focused on "the traditional and contemporary music and dance of the world's women."
I don't remember exactly how we first heard about them, but I think we first heard them in college when someone ordered their album A Circle Is Cast (subtitled "Rounds, Chants and Songs for Celebration and Ritual") from the Ladyslipper catalog.
That album and the associated songbook (and, later, the group's other related album and songbook Fire Within) were, iIrc, among Jim M's main inspirations for putting together the first roundsing at Swarthmore. Circle features twenty-two songs, about half of which are rounds; we still sing half a dozen of them regularly at roundsings.
I mention all this because I just noticed that six of Libana's albums are now available at the iTunes Store, including the three rounds-and-chants albums I own. Lovely harmonies; moods ranging from contemplative to joyful; songs that are generally short and easy to learn. Good stuff. And although many of the songs will probably be of particular interest to Wiccans, you don't have to be Wiccan to like them. (And I should note that the group's other albums tend to be more focused on traditional women's music from around the world (especially the Balkans and the Middle East), and not so much on rounds and chants.)
I've put together an "iMix" sampler, listing my favorite Libana pieces to listen to (which aren't necessarily my favorites to sing, and not all of them are rounds). That playlist is drawn from the three albums I own: A Circle Is Cast, Fire Within, and Night Passage.