The underground railroad that crisscrosses the United States, connecting the apartments and rehearsal spaces and basement studios of indie musicians who seem to make a living out of thin air, has created its own social dynamic. It seems naive to talk about "scenes" in terms of single cities, like Austin or Chapel Hill (the current fave rave is Omaha), because the scenes are as fluid and overlapping as the music.

Singer-songwriter Tara Jane O'Neil emerged from the close-knit, lo-fi avant-garde of the Louisville, Ky., underground, whose most famous product, the "ugly rock" band Slint, contributed a lot of ideas (as well as a few members) to the Chicago post-rock movement led by Tortoise and Gastr Del Sol. In the early '90s, O'Neil played bass in Rodan, a highly regarded Slint acolyte unit which itself splintered into various projects, each with its own sonic agenda. O'Neil's personal vector led to New York, where she teamed with like-minded miniaturists in a number of marginal groups.

By the time she released her second solo album, "In the Sun Lines," last year, O'Neil was a seasoned traveler on the railroad. Along the way, the free-noise aesthetic she developed with Rodan had been leavened by the blanched acoustic folk that swept the Northeast in the mid-'90s. The record contains real songs that often channel recognizable forms (bossa nova, murder ballads, soft pop) but never turn out the way you expect them to. Her constructivist approach is geared toward mood rather than meaning, and despite the cut-rate trappings, the album contains the kind of rich, emotionally wet music that's made Arab Strap the darlings of the eternally pessimistic.

Recently, O'Neil teamed with Daniel Littleton, leader of the Brooklyn-based chamber-rock band Ida, for an album of mesmerizing minimalist instrumentals called, appropriately, "Music for a Meteor Shower." Like O'Neil's, Littleton's songs seem built rather than written, though he's more tolerant of traditional melodies and his lyrics are as comfortable on the page as they are coming out of his mouth.

Performing as a duo and separately, these two may prove to be a dangerous combination for borderline suicides, but as regular riders of the underground rails, they've used their experience and open minds to create original and compelling music. Hop aboard, and watch your step.