Forget labradoodles, boob jobs and voracious cocaine habits. The current essential celebrity accessory is a Web 2.0 strategy. Facebook pages, Twitter feeds, MySpace blogs... Tabloid notoriety is nothing if it doesn't have social media to back it up.
All too often, though, the actual celebrity doesn't have much to do with all this. They have their 'people' handle that sort of thing for them. Yet some do get their keyboard-fingers dirty and dive in -- notably the five picked out for this feature.
Don't let the presence of Mr Demi Moore fool you into thinking this is purely about celebs with monster followings on Twitter. It's about how they're using social media in interesting ways, and what they're doing with their online fame. Read on.
Even in tabloid-land, Kutcher is now probably more famous for his online activities than he is for being that toy-boy who weirdly gets on with his missus' ex-husband. He famously became the first Twitter user to have more than 1 million followers earlier this year, and now has nearly 4 million.
What's he doing with that audience? Well, boasting about his wife's fine ass, yes, but also other things. He promoted World Malaria Day and promised to donate 10,000 mosquito nets to the charity, while rallying other celebrities to the cause. What's more, he's shown a shrewd awareness of what this new power means, claiming, "Individuals are becoming consumers and editors of the media -- it has and will forever change media."
Don't forget, either, that he's also got a sideline in tech startups, having backed (admittedly not world-beating) VoIP firm Ooma, while more recently launching an animated Web show called Blah Girls.
Remember Trent Reznor? You know, the guy from Nine Inch Nails. Bit brooding. Sees fauna as bedroom role models. Yeah, that one. Is he still around? Yes he is, and he's providing a startling case study in how musicians can use the Web to forge an even stronger relationship with their fans and, yes, sell music.
Examples? He kicked off 2009 by giving away 400GB of HD footage of his band's latest tour to fans, inviting them to edit, remix and generally mess around with it to their hearts' content. This at a time when some other artists and labels were filing takedown notices to remove fan-shot mobile videos of their gigs from YouTube.
He then made the latest NIN album available in a digital format bundling music, images, lyrics and videos months before Apple invented resigned from Twitter in protest at "idiots". Well, you can't have everything.. He launched an blending social networking, fan-uploaded content and Google Earth. He built an email list of 2 million fans. And then
The most electable thing about Gordon Brown? His wife. Sarah Brown has a low-key reputation, but she's also a well-respected PR boss, who was quick to catch on to the potential of Twitter. Like Ashton Kutcher, she clearly understands what can be done with a large following (although thankfully, unlike Ashton she doesn't Twitpic photos of her spouse bending over in a bikini).
Anyway, running neck-and-neck with Stephen Fry to be Britain's most-followed Twitter user is one achievement. Doing it in a determinedly un-political fashion is another. Brown chats about what she's up to, but she also retweets and replies to people, with a dash of humour too ("HM Queen is First Lady -- I am wife of PM!").
But the real reason for making this list: by building a 900,000+ Twitter following and engaging with it, Brown has built a base for campaigning. Not just party-political campaigning, but promoting the charities she works with. Americans can cite Barack Obama as a prime example of a Web-savvy politician. Sarah Brown might not have been voted into anything, but she's the nearest equivalent us Brits have got.
What, the Vin Diesel? Bald fella, muscly, appears in films where the cars out-act the stars? Why yes. Ever checked out his Facebook page? Vin has more than 7 million fans on the social network. 7 million! It's not uncommon to see 25,000+ 'Likes' on his status updates, and thousands of comments.
This isn't something you can put down to rabid Fast & Furious fans. Diesel has built such a following because he's almost using Facebook as a blog, writing regular, very long status updates about what he's up to, anecdotes from his career and photo uploads of his travels. His feed looks like a friend, not a marketing campaign.
That's one of the biggest lessons of this feature: celebs who get the Web think of it as a way to communicate with people, not just pimp stuff to them. But paradoxically, the more time and effort you spend not pimping stuff to fans, the more effective it is when you do have something to promote.
Chad Ochowhoco? He might not be a household name in the UK, but Cincinnati Bengals wide receiver Ochocinco is a trailblazer for the way sport stars use social media. Not that American football's governing body, the NFL, is entirely happy about that.
Chad uses Twitter heavily, and has built up a following of nearly 400,000 followers -- small beer next to Kutcher, but impressive for a sport star. He tweets regularly, and webcasts live using Ustream as well.