Actors and musicians are always trying to swap places, often with hilarious consequences (as long as you didn't pay for a ticket). Madonna in Body of Evidence? Keanu Reeves in his inexcusable band Dogstar? I think not. But Tim Robbins is a thoughtful, conscientious kinda guy, and he can even claim a bit of a folk-singing heritage via his father, Gilbert. And he put together the impressive soundtrack for his movie Dead Man Walking. And he played a right-wing folk singer in the political satire Bob Roberts.

Mark Ronson & The Business Intl, The Bike Song (Sony Music)

There are ways and ways to make novelty retro-pop. Mark Ronson, for example, has absolutely nailed it here. This song, with its almost unbearably sunny Lovin' Spoonful-styled harmony vocals slathered over an early-Nineties pop-hip-hop breakbeat with jaunty raps from Spank Rock, should be awful – should be so calculatedly faux-naif it makes you hurl – but it's just done with so much invention, so much out-and-out glee and such great hooks that it's completely irresistible and delicious.

Hackney’s Empire is the perfect venue for pan-Atlantic producer/hipster Mark Ronson’s vehicle The Business Intl. New album Record Collection is an aural revue – with guests ranging from Eighties idols Boy George and Simon Le Bon through Wu Tang’s Ghostface Killah to Andrew Wyatt of Swedish dance-poppers Miike Snow. A former musical hall, it’s a fitting showcase for Ronson’s portmanteau sensibility. It’s as if variety was primed for a comeback at this show, the second of six smallish-venue road-test dates. In support, his Business Intl colleague, Rose Elinor Dougall, trod the boards on the heels of her recent solo album Without Why.

After only a couple of songs there are shouts from the audience to turn Mulatu up. But these people have missed the point. The clue is in the name of the instrument he's playing: the vibraphone, or vibes for short. The word "vibe" has long been slang for “a good feeling” or a mood, and that’s precisely what its role was in last night’s concert; to add some of that ambient mysteriousness intrinsic to the five-note Ethiopian scale.

I Am Kloot are a band it’s hard not to like in an almost personal way. The Manchester-based trio exude warmth, northern charm and a sense of self-contentment, seemingly impervious to the fact that they still haven’t made it as big as everyone thinks they should. Maybe that’s unsurprising. With the band’s leader in his forties, maybe it would be odder if they weren’t making music for reasons other than pampering egos. And it shows.

“Thank you for waiting. I know some of you have been waiting a long time – about seven years – but it takes me a while to get things done.” Thus did singer/songwriter Hayley Willis greet the audience at her return to active service. Two Willis albums have bookended that seven-year period: 2003's acclaimed Come Get Some, her debut for 679/XL, and its excellent follow-up, Uncle Treacle, released on 4 October on her own Cripple Creek label, for which last night's performance acted as a launch party.

My, haven’t they grown? In the several years (perhaps even a decade) since I last caught Placebo live, they’ve gone from being a scrawny three-piece with a somewhat thin sound – for much of the gig, I saw, they didn’t even have a bassist on stage – to become a properly equipped rock band with six on-stage members: here, on the first of two nights in south London, the band consisted of the regular trio, plus three side-persons on guitars, bass, keyboards and violin. They made quite a noise, blasting out satisfyingly slabby slices of sound.

Just before Edwyn Collins came on, the throbbing bassline of Chic's "Good Times" rumbled out across the packed South Bank auditorium. As a statement of intent it was pretty clear. Having suffered two debilitating brain haemorrhages followed by a bout of MRSA in 2005, Collins is understandably delighted to be gigging again. To paraphrase the old stand-up comedy opening salvo, he is probably delighted to be anywhere again. Some paralysis down his right side means he walks with a fetching silver-topped stick and does not play guitar onstage any more, but nothing held him back. His rapturously received, emotionally charged performance was captivating.

This was a warm and convivial evening in the company of the American folky-rootsy-rocky singer and songwriter Josh Ritter. His band made a rich noise, and his voice was keen and true, almost every lyric clearly audible. At the end of this, the last night of Ritter’s UK tour, the crowd – he seems to have a strong female following - were on their feet, and there were several calls of, “We love you, Josh!” from the stalls.

A soundtrack of "Purple Haze", "Hey Joe" and other eternal Jimi Hendrix hits, is currently drifting out of the Snap Gallery along the swanky Piccadilly Arcade in Mayfair. A boutique exhibition space, Snap sits incongruously amongst purveyors of "fine" jewellery and gentlemans’ tailoring and its front windows are transforming the chi-chi mall with Gered Mankowitz’s photographs of the Sixties guitar genius, Hendrix.