With major publicity and sales boosts from its recent Grammy triumphs, a successful concert tour just concluded and an even more ambitious one on the way, the O Brother, Where Art Thou? roots music phenomenon just keeps getting hotter. Although some critics expressed dismay that the soundtrack had rolled over titles by Bob Dylan, U2, Outkast and India.Arie to win the album of the year Grammy, the creators of O Brother could rightly claim that they had caught the ear of the people.

In the week following the Feb. 27 Grammy telecast, the album sold 209,227 copies, soaring from a still impressive 58,331 sold the week before. In doing so, the album returned to the No. 1 spot on Billboard's country album chart and rose to No. 2 on the overall album ranking. O Brother has been on the charts for 65 consecutive weeks and has sold an estimated 4.2 million units.

There were also substantial post-Grammy sales jumps for other albums stylistically within O Brother's penumbra. Down From the Mountain, the spinoff album that features O Brother artists -- and which provided the title for this year's sold-out tour -- more than doubled its sales of the week before, moving up from 4,804 to 10,101 copies. Up also over the previous week were Alison Krauss' New Favorite, Nickel Creek's self-titled collection, Earl Scruggs' Earl Scruggs & Friends and Patty Loveless' Mountain Soul.

All the artists involved in these boosts probably benefited from recent high-profile exposure. Krauss and Scruggs were among the latest Grammy winners. Loveless was on the Down From the Mountain tour. Nickel Creek was featured (as were Krauss, Scruggs and others) on the recently aired PBS special, All Star Bluegrass Celebration.

There are other indicators of O Brother's staying power. The album is currently No. 1 on both the Amazon and Barnes & Noble retail Web sites, and the O Brother, Where Art Thou? songbook ranks as the No. 4 top-seller on the sheet music Web site, sheetmusicplus.com.

Ralph Stanley, whose promotional stock soared after he won two Grammys and performed on the show, will capitalize on these happy circumstances with at least two albums this year. The first is a live album recorded last year, Dr. Ralph Stanley & The Clinch Mountain Boys Live at McCabe's Guitar Shop, which is due out March 12. The second is a still-untitled collection produced by O Brother's musical mastermind, T Bone Burnett. On the latter album, Stanley is backed not by his own band but by musicians who played on the O Brother soundtrack and the Down From the Mountain tour.

Dobroist Jerry Douglas, who shared in O Brother's Grammy sweep and who distinguished himself for musical support and versatility on the tour, will release the album Lookout for Hope on May 5.

A spokesman for Valley Entertainment, which distributes blues singer and O Brother cast member Chris Thomas King's latest album, The Legend of Tommy Johnson, Act 1, says sales are doubling every week. He would not specify total sales, but he noted that the company has had to do a lot of repeated restockings at record stores since these outlets tend to carry only two or three copies of any one blues album. King was on the first tour and plans to be on the second one as well, which is tentatively set to start in June.

Dan Tyminksi, also a mainstay of the tour, won the best country collaboration with vocals Grammy (with Pat Enright and Harley Allen) for "I Am a Man of Constant Sorrow." His management company, DS Management, reports that sales of his album, Carry Me Across the Mountain, have moved up gradually and now total around 25,000 copies, a large number for a bluegrass album.

Blue Grape Merchandising of New York handled souvenir sales at the

Down From the Mountain shows. The offerings included the O Brother and Down From the Mountain albums, "prisoner shirts" and ball-and-chain key chains (symbolizing the three escaped convicts whose fortunes the movie chronicles). "The bestselling item by far was the [souvenir] program," says Blue Grape's Felix Sebacious. "It was really fantastic. ... We were able to include photos and bios of all the artists performing. ... The Coen Brothers [who produced the movie O Brother, Where Art Thou?] were gracious enough to contribute the introductions for us." The program was priced at $10. Sebacious declined to say how many programs his company sold but stresses it was "thousands and thousands."

In terms of market activity, Sebacious says, he was surprised at "how successful the Northeast was," both for albums and merchandise. "You come into a market like New York City, which you would not think is the typical demographic for attending a concert like this, and it was a tremendous reaction."

O Brother has not yet sent cultural shock waves across America's campuses, at least not in the way the folk music boom of the late 1950s did. Namath Gaskin, member services assistant for the National Association for Campus Activities, says, "That type of music has always had a niche in the college market. And from what I've seen, it's neither increased nor decreased [because of the album]."

Immortal Entertainment, the Santa Monica, Calif., company that staged the original Down From the Mountain tour, has not yet released the dates, cities and lineup for the second leg. It is expected to have more stops, however, than the 19 shows that made up the first circuit. A spokeswoman for Immortal says she doesn't know if Barnes & Noble will sponsor the next tour, as it did the last one. She did confirm that Ricky Skaggs has been added to the talent lineup.