UK2.net have a special offer on domain names. Search for domain names using the search box, then add the .co.uk and .com to your basket, and they will cost you just £10.
This is a saving of 12% off normal prices! The domain names will be renewed at the USUAL rate, however the usual rate is one of the best out there anyway: just £5.99 per year for a .com domain and £2.69 per year for a .co.uk domain.
The T&Cs say that the offer is only valid until June 2009, but it is still working and I've recently used it successfully. ENJOY!