RjDj’s Michael Breidenbruecker, also a Founder last.fm, has certainly opened up the avenues for sound apps on mobile platforms. The startup’s apps have become platforms for musicians, but are gradually evolving into augmented reality mobile apps.

Most recently the company partnered with screenwriter Christopher Nolan on Inception: The App, which reached 4 million downloads. The amount of “dreamtime” (time spent listening to the app ) was over 94 years. The average listening time per session is over 30 minutes. This was not your average app!

UK-startup GroupSpaces, which last year secured a $1.3m Seed round from a star-studded roster of investors including Index Ventures, Dave McClure, Chris Sacca and Simon Levene, has become a ‘Silicon Roundabout’ stalwart. Cofounders David Langer and Andy Young met at Oxford university and quickly realised they could build a better way for University groups to interact, so post-graduation they packed their belongings into a van and headed to London to join the Moo Studios crew on “The Roundabout” a couple of years ago.

They are now on well over 1.6 million group memberships with their simple online management and administration tool for real-world groups. Simpler than Yahoo! groups for mailing lists or member records in Excel, the site has a payments collection system built in and is free for groups with less than 250 members. Revenues come from a combination of premium accounts, targeted advertising and transaction commission from payments made through the site.

Back in January GoSquared arrived on the scene to attempt an assault onChartbeat’s realtime analytics territory.

While Chartbeat has raised an impressive $3 million Series A financing with a glittering array of backers including Betaworks and Ron Conway, GoSquared has had a more modest seed funding round from Passion Capital.

Founders James Gill, James Taylor and Geoff Wagstaff range between 19 and early 20s, so pretty young founders. Even so, their product has been attracting plenty of attention, especially amongst startups in London, their home turf.

Shutl, an on-demand delivery platform that aggregates transportation carriers so they can deliver something in an hour, recently took £650,000 ($1m) investment round from Hummingbird Ventures and others. It’s been piloting its service with Argos, a leading high street retailer in the UK.

Shutl was formed by Tom Allason, previously founder of eCourier.co.uk. We went to interview him at his office near “Silicon Roundabout” – the cluster of tech companies in East London – in our series of videos we’re calling The Roundabout Tapes.

The rise of location-based apps has been so rapid that there are a slew of products coming onto the app stores most of the time. But few have gone to the trouble of realising that by targeting a passionate user base in one area they may get some head-room over the competition. Hey, it works in the Valley, why not elsewhere?

That’s the been strategy of young London-based startup Area Now, which bills itself as a ‘short-notice event recommendation service’ for nearby events. Their iPhone app now in Beta (combined with the site), effectively crowd-sources events from people nearby who want to find out where the latest happening club or event is. You can download the app from iTunes here or start adding events direct on the site.

Late last year Semetric, the startup behind the Musicmetric analytics service, secured a “significant round” of funding led by Pentech Ventures (terms were undisclosed) but that gave the company a good “two-year runway” to expand its data collection infrastructure and applications and grow the team.

It’s now powering Musicweek’s weekly Artist Buzz Chart, and rolling out its measurement and analytical tools, especially aimed at the music industry, monitoring consumer activity on social networks, P2P file-sharing networks, alongside reviews, comments you name it.

In addition, they are forming part of the substantial group of music-based companies in the ‘Silicon Roundabout’ tech cluster area of East London which includes Last.fm, Soundcloud, Songkick, Fizzback and Mixcloud among others.

We spoke to them as part of our “Roundabout Tapes’ series of interviews.

Continuing our series of interviews with companies in the Silicon Roundabout area of London (we’re calling this The Roundabout Tapes), we went to interview Mixcloud.

The on-demand radio service wants to be the ‘YouTube of radio’. Online radio is very much a digital media orphan; languishing in a fragmented space while innovations in other aspects of streaming media have come thick and fast over the last few years.

Continuing our series of interviews with companies in the Silicon Roundabout area of London (we’re calling this The Roundabout Tapes), we interviewed Clearer Partners.

Clearer is a specialised tech/media consulting company but is also doing a startup. The soon to launch Frameblast is aimed at SOHO companies who want to handle video in a smarter way along the lines of Media Silo. Companies can upload their archives into the cloud and use it like a Google search engine for their archive, with tags galore.

Squadify is a stealth-mode startup planning to try and disrupt the world of casual team sports. We interviewed the company as part of our new video series, The Roundabout Tapes, documenting the startups in the area of East London that has come to be known as Silicon Roundabout.

Squadify is a startup aiming to allow people to find sports teams they want to play in, or even form. Close to a kind of ‘Meetup for sport’, the site is still in pre-alpha, but is aiming for a launch in the crucial Summer sports season.

We met up with co-founder Andrew Davey to find out what the startup is planning. Like a lot of tiny, bootstrapped startups in the Silicon Roundabout area, Davey, along with cofounder Nick Casey, are banking that they can scale up on the back of social buzz and integration with Facebook.

Many have talked about the explosion of tech startups in the East of London, which has come to be known colloquially as “Silicon Roundabout“. But who are they? We’ve been writing about the emerging tech cluster there since it’s first stirrings in 2008, so we’ve decided to start documenting them for TechCrunch TV. And with the help of our video crew in the shape of producer (and startup founder, even) Chris Leydon and camera guru Olly Newport, we’ll be releasing the videos over the next few weeks.

Our first interview was with Azeem Azhar, CEO and founder of PeerIndex, which moved into the area recently.