Thanks to Alex at Nielsen Online for these 2008 unique user stats for UK social media sites. I was hunting around for these but couldn't find them – they must have been published somewhere.

Anyway, a useful reference as I am doing some research around this. Was struck by the popularity of the blogging platforms.

Rank

Social Media Site

Unique Audience (000)

Active Reach (%)

1

Facebook

17,645

48.7

2

YouTube

14,508

40.1

3

Wikipedia

12,793

35.3

4

Blogger

7,525

20.8

5

MySpace

5,361

14.8

6

Yahoo! Answers

5,298

14.6

7

Bebo

4,324

11.9

8

WordPress.com

3,498

9.7

9

Flickr

3,066

8.5

10

TripAdvisor

2,933

8.1