They're the guys who are usually grouped under a single title: the rhythm section. The guys who receive critical praise in phrases beginning with "The rhythm section propelled the rhythm forward in high gear ..." etc.

Not much in the way of individual personality there. Of course, the pianists have an easy escape route. They can do solo albums and performances, relying on what is, after all, an orchestral-like array of sounds in a single instrument; or they can lead the ubiquitous piano trio (actually nothing more than a sneaky way to describe a rhythm section).

Guitarists have similar ways out, aided by the rock 'n' roll decades giving their instrument plenty of charismatic sexiness. But it's tougher for bassists to step into the spotlight - Charlie Haden's high visibility notwithstanding - and drummers seem to vary from slam-and-bang leadership to providing the understated spark that sets the music in motion.

Drummer Roy Haynes has taken the latter route for most of his illustrious career. In "Birds of a Feather: A Tribute To Charlie Parker" (* * *, Dreyfus Jazz), he reaches back to his earliest days in jazz, fronting the all-star quintet of trumpeter Roy Hargrove, alto saxophonist Kenny Garrett, bassist Dave Holland and pianist Dave Kikoski. Haynes' youthful demeanor and skillful drumming make it hard to believe he was a member of Parker's quintet from 1949 to 1952, and that he played with Lester Young before that. But, at 75, he continues to be one of the most vital and influential drummers in jazz.

The temptation in a tribute to Parker would have been to simulate some of the classic bop items of the '40s and '50s. Although Haynes has included such familiar items as "Ah Leu Cha", "Moose the Mooch" and "Yardbird Suite", the interpretations - undoubtedly aided by producer-trumpeter-arranger Don Sickler - frame the music in settings ranging from quintet bebop to Coltranesque modality on "My Heart Belongs to Daddy" and a '60s-era Miles Davis-styled rendering of "Now's the Time". Urged forward by Haynes' seminal drumming, the soloing is universally compelling, with Holland an additionally powerful force, both as a soloist and as a symbiotic rhythmic partner.

Bassist Avishai Cohen, who has recently been heard prominently with Chick Corea's acoustic trio, deals with the bassist-in-the-background problem in decisive fashion on "Unity" (* * * 1/2, Stretch/Concord Records): He moves to the piano.

As it turns out, the decision was not especially difficult because Cohen started his career as a pianist. He found, from the piano chair, that he had "more control over the creation of space and percussion in the music ... more involvement in the live impact of the harmonic compositions".

Cohen would probably be the first to note that his level of piano proficiency won't offer significant competition for Corea. But in this collection of his emotionally charged originals, he does use the piano as the central source from which his music flows - a source that opens and closes around the instrumental tributaries of his players. Cohen calls his group the International Vamp Band, and many of the pieces do, indeed, rely effectively on the repetitious, largely modal patterns that musicians describe as "vamps".

But the key part of the name is "international", because this is a truly global jazz collective. Cohen, trombonist-vocalist Avi Lebovich and bassist Yagil Baras are from Israel; trumpeter Diego Urcola is from Argentina; saxophonist Yosvany Terry is from Cuba; and drummer Antonio Sanchez is from Mexico. What they have to offer is a transcendent example of the capacity of music in general, and jazz in particular, to reach beyond geographical and political boundaries. When Cohen asserts his belief that music "serves a crucial role in uniting people and breaking down barriers," he offers the perfect description for what the International Vamp Band's maiden recording effort is all about.

Pianist Jacky Terrasson and vibraphonist Stefon Harris were top-level performers so early in their careers that neither has actually spent much time serving as backup rhythm-section players. On "Kindred" (* * * 1/2, Blue Note), however, they have taken on an even more difficult task - that of challenging each other's high-level skills in a competitive musical partnership, accompanied by bassist Tarus Mateen and Terreon Gully or Idris Muhammad on drums.

Both Terrasson and Harris pass the test brilliantly. The way they deal with each other offers an intriguing contrast to what is perhaps the most familiar piano-vibes encounter - the work of John Lewis and Milt Jackson in the Modern Jazz Quartet.

The polarity between Terrasson and Harris takes a different slant, however, with Terrasson (unlike Lewis) playing the more emotionally aggressive, rhythmically dynamic role, and Harris (in contrast to Jackson) offering thoughtful, hard-swinging but introspective qualities.

That inverse association aside, Terrasson and Harris clearly stimulate each other and bring out the best in their individual playing. They enhance those qualities with a program that places some familiar material in offbeat but revelatory settings.

"My Foolish Heart", for example, is gradually assembled in reconstructed bits and pieces; "Summertime" is harmonized in reference to a contrasting melodic line; "Body and Soul" - in strikingly unusual fashion - becomes the source of a brisk, up-tempo rendering; their duet on "What Is This Thing Called Love?" offers the familiar theme in pointillistic fashion. It's not exactly the sort of playing that drifts into the background - especially during the racetrack romp through "Tank's Tune" - but it's precisely what to expect when two world-class players get together in an improvisational exchange.