The world of tech can be a strange place. It's a place where zeroes become heroes, where public enemies become pillars of society and where tabloid villains turn out to be perfectly legitimate after all. Come with us as we discover the sites, services and (ahem) personalities who became notorious on the net and then tried to come back.

1. BitTorrent

BitTorrent used to be a byword for movie piracy, but BitTorrent Inc has been making a concerted effort to go straight. BitTorrent Bundles, which combine free and protected content, have been used by Madonna, Eddie Izzard, De La Soul and Public Enemy to promote their work.

The protected content is unlocked when users provide an email address, but soon BitTorrent Bundles will offer content that is unlocked in exchange for money, with BitTorrent taking a cut of the proceeds.

2. Kim Dotcom

Kim Dotcom
You might want to wait until baboom.com has more albums than just Dotcom's not-so-good Good Times

The shy, retiring Mr Dotcom is the copyright industries' public enemy number one: his file sharing website, Megaupload, was shut down by the US Department of Justice in 2012, and he's currently being sued by six Hollywood film studios and facing possible extradition to the US.

Undeterred, Dotcom is planning to launch a legitimate music streaming service, baboom.com, later this year. Until the formal launch there's only one album on it: Dotcom's own (bloody awful) Good Times

3. Ashley Madison

Ashley Madison is the kind of website you'd expect to see advertised in the darker corners of the web: it's a dating site set up specifically for people who want to cheat on their partners. However, through a combination of high-profile advertising, affiliate marketing and PR stunts, the site has become part of the mainstream: it boasts more than 21 million members in 30 countries.

4. Napster

Napster
Napster still provides music to its users, but now it does so legally

Napster and its imitators destroyed the music business as we knew it: the lure of free music and the infinitesimal risk of getting caught meant an entire generation stopped paying for tunes. At its peak it had over 80 million users. Years of litigation finally killed the service in 2001, but the name and logo live on: today it's a Spotify-style subscription music service.

5. Kazaa

Kazaa was a blatant attempt to mimic Napster without falling foul of the same legal problems that killed the file-sharing pioneer, but that didn't stop the music business from suing it silly. Like Napster it went on to become a legal subscription service, but unlike Napster it didn't survive. Its earliest backers did though, and Niklas Zennström and Janus Friis went on to create Skype and Joost.

6. The Pirate Bay

Pirate Bay
Forget surfing the web, TPB sails the illegal high seas

Anyone who thinks The Pirate Bay wasn't largely based on piracy is rather naïve. If all those torrent users were really sharing Linux distributions, Linux would be the most popular consumer OS on earth - but TPB did try a number of things to clean up its act, such as The Promo Bay.

The Promo Bay showcased up-and-coming bands that were quite happy for people to torrent their stuff, but even though it was moved to a separate domain it still ended up blocked by UK ISPs. That blocking was removed in late 2012 and UK internet users can now access The Promo Bay, but not its piratey parent (well, not easily).

7. Craigslist

Craigslist didn't start off as an online bad guy: the listings service began as a way to publicise local events and became a cheap and cheerful home for classified ads. Unfortunately the more adult ads caused controversy, with Craigslist accused of facilitating prostitution and even sex trafficking. In 2009 Craigslist decided to clean up its listings and binned the adult services categories in the US and Canada.