1GB Mobile Web
Unlimited Virgin to Virgin
Standard Price: £15.32/month.
New customers can get this as well as existing, as long as you have a package with Virgin Media - for example a Broadband/Cable TV/Home Phone package.
If they don't give it you to start with, ask to talk to retentions (who are UK based) and will offer you it immediately after referring to Tesco's 500/unlimited/500.
This is different to the 800 offer as it is open to more people.