MySpace:Social networking site MySpace is particularly known for its focus on the music scene as a way of building up membership.
Billing itself as an "online community that lets you meet your friends' friends", MySpace allows members to share photos, journals and interests with mutual friends. Intermix Media, the owner of MySpace, was bought by Rupert Murdoch's News Corporation for $580 million last year.
The move was widely seen as an indication of the growing importance of an online presence for media companies. In announcing the purchase in July 2005, the company estimated that the addition of MySpace, and Intermix's network of other sites, would increase its web traffic to more than 45 million unique monthly users.
YouTube
The world's largest online broadcaster, founded in February 2005, was purchased earlier this year for $1.65 billion by Google, the world's largest search engine. Unlike sites such as MySpace and Bebo, YouTube focuses its activities on watching and sharing videos.
It is currently serving 100 million videos per day, with more than 65,000 videos uploaded on a daily basis. According to some estimates, it accounts for 60 per cent of all videos watched online, with nearly 20 million "unique" users per month.
The site includes video embedding among its services, which lets users insert a YouTube video into MySpace accounts, blogs or other websites, where anyone can watch them. Users can also opt to broadcast their videos publicly or share them privately with friends or family.