I've been trying to take advantage of an offer on Silverjet, but it turns out it's only for travellers coming from the US. So in the spirit of transatlantic cooperation here are the details:
You can read my trip report here:
Silverjet LTN-EWR Trip Report With Pics (by AabFlyer Feb 7 2007 in Trip Reports)
They've come up with a "freequent flyer" promotion on tickets bought in the US. If you are a member of a frequent flyer program (doesn't matter what the airline is), you give them your details and they give you a "Freequent Flyer" code which entitles you to receive a free flight when you purchase any round trip ticket from Newark to London. I think you can also just buy a single and get it half price. You have to book by midnight Friday 25th May 2007, but travel doesn't need to be till the end of the year.
Unfortunately the promotion doesn't work for us in the UK (I called and asked and you have to register on the US site to get the code and that presumably only works if your registration details are in the US.)
If anyone knows how to get round this, on the other hand, do pls let me know...