Anywork Anywhere
Contains a good selection of Internet cafes in London.
http://www.anyworkanywhere.com/ccuklondon.html

Blaze Computer Rental
Short term computer rental specialist.
http://www.blazecomputers.co.uk/

City of London
The Square Mile has been turned into one big outdoor Wi-Fi network.
http://www.cityoflondon.gov.uk/

Cybercafes
Index of Internet cafes worldwide.
http://www.cybercafes.com/

easyInternetcafe
A well known chain of cybercafes.
http://www.easyinternetcafe.com/
http://www.easyeverything.com/

Google Space
Check your email, learn more about Google's latest products or provide feedback about them, all for free, while you wait to board your flight at Heathrow Airport's Terminal 1.
http://www.google.co.uk/googlespace/

Home PC Rental.co.uk
Laptop rental at short notice.
http://www.homepcrental.co.uk/

Kropla.com
Contains information about connecting to the Internet while abroad using a global ISP.
http://kropla.com/roaming.htm

Online 4 Free.com
Free Wi-Fi network along the Thames.
http://www.online-4-free.com/

Road News
Hints and tips for travellers with laptops.
http://www.roadnews.com/

Thames Online
Offers high speed internet access along the river Thames.
http://www.thamesonline.com/

The Cybercafe Search Engine
Just as it says.
http://cybercaptive.com/

Visit London
A comprehensive index of Internet cafes in the capital.
http://www.visitlondon.com/directory/search?categoryNodeId=974&browse=true&keyword=