FOR THOSE readers who were glued to BBC1 last night, I should stress that Imani Coppola is not to be confused with Imaani, Britain's plucky Eurovision contender. Too talented to be smirked at by Terry Wogan, Coppola fuses spangly pop, sparky country and socially aware rap to sound like Ani DiFranco teaming up with Deee-Lite, De La Soul and Beck. Besides, she'd be disqualified from Eurovision for calling her debut album Chupacabra (Columbia). The Spanish judges might take exception to a title that translates as "goatsucker".

At the London Garage on Tuesday, Coppola's band couldn't recreate the flock of sounds that flits through Chupacabra. Only "Legend of a Cowgirl" and "It's All About Me, Me and Me" stood out from an hour of pleasant but hazy funk, and it was the performance rather than the songs that stuck in the mind on the bus home. But what a performance it was. Coppola bounded onstage wearing a Supremes wig, a checked dress and half a tub of glitter around her eyes. With the aid of two water pistols, a toy banana and an 18-inch-high inflatable man, she posed and flirted like Bugs Bunny disguised as Shirley Temple. She was a one-woman girl group. And just as she was in danger of wackiness meltdown, her fiddle playing and her clear voice reminded us of the ability behind the glitter. She finished the show by leading her band in a conga line through the audience, and you don't see that at Verve concerts.

A year after Jeff Buckley drowned in the Mississippi at the age of 30, his death still seems more heartbreaking than that of almost any other rock star. Not just because he was so young and gorgeous - they usually are - or because Tim Buckley, the father he met only briefly, died even younger, but because his music hinted all along that his stay on Earth would be short. His only completed studio album is named Grace, and alongside the title track there is "Last Goodbye", "Eternal Life", Leonard Cohen's "Hallelujah" and Britten's "Corpus Christi Carol". Almost as soon as Grace was released in 1994, no journalist could resist writing about Buckley in religious terms: the looks of an angel, a voice from heaven, his concerts a divine experience.

This may seem to be nothing more than macabre irony, but these descriptions do give some measure of Buckley's talent, and it's the loss of this talent that makes his death so lamentable. Grace is so intense that it is painful to accept its maker is no longer around, but at the same time, it seems somehow correct, as if this beauty were too rare and valuable for us to hang on to for long.

Buckley's most striking gift was his eerie, electrifying singing. It was matched, nearly, by his disregard for conventional song structures, and by the shimmering webs of guitars and strings that he and his band wove. Like Radiohead, he made what might be called "progressive rock" without making you reach for earplugs, and apart from Radiohead he had no peers when it came to applying an astonishing, multi-octave voice to music that didn't shy from sincerity, seriousness or complexity.

The follow-up to Grace was to have been My Sweetheart, the Drunk. A first attempt was recorded with the visionary Television leader, Tom Verlaine, but Buckley was unhappy with it, and determined to start from scratch. He made some demo tapes in preparation for a second try, and his band were flying into Memphis to flesh them out on the day he was killed.

Now we can hear all the stuff he didn't want us to hear. His mother and his friends have compiled one CD of the Verlaine recordings, and another of Buckley's last demos. And on first listen, Sketches (for My Sweetheart, the Drunk) (Columbia) is a cruel disappointment. CD 1 isn't a bad listen, but nowhere is there the magic or the gravity-defying ambition that characterised Grace. Nowhere are there any intricately shaped arrangements. Even Buckley's voice is strained. His falsetto doesn't sound like an angel, it sounds like Sting.

Sketches is the work of a grungey guitar band: a bit like Smashing Pumpkins, a bit like Nirvana (compare "Nightmares by the Sea", which is on both discs, with "Come As You Are"), and quite a lot like Tom Verlaine. "Everybody Here Wants You" is the exception. It's Simply Red with a guest appearance from Eric Clapton.

Hastening to CD 2, the demo disc, we find some cacophonous experiments. From "Murder Suicide Meteor Slave", with its plings and sproings and great farts of overdriven guitar, to the Iggy Pop-style trash rock of "Your Flesh Is So Nice", this could be Jim Morrison jamming with Frank Black after a night at the pub. Buckley had a lot of work to do to complete the album.

A few hours later, Sketches sounds very different. If you don't make the mistake I did, and put it on straight after you've listened to Grace, then it stands up as a powerful record in its own right. Yes, it's just American alternative rock, but you'll be lucky to get anything more alluring, inspired, or affecting from another American rock band this year. And after all, Tim Buckley kept changing musical styles. Why shouldn't Jeff switch direction, too?

Even CD 2 is a fascinating document, but it's not one to listen to very often, bar the jazzy rendition of the Rhodes-Hayes classic "Satisfied Mind". Here, Buckley's voice is at its acrobatic best, and the emotive punch we'd wish from him is delivered by the album's closing lines: "One thing's for certain, when it comes my time/ I'll leave this world with a satisfied mind." If only.