...and ucl, icl, kcl, durham, st andrews, trinity dublin, nottingham...
to be honest, it really depends what you're looking for. your best bet is to read through as many prospectuses (prospecti?) as you can, and find the uni you feel most comfortable at.
the times good university guide is quite helpful - http://www.timesonline.co.uk/section/0,,716,00.html
Oxford, Cambridge, Leeds (Languages), Exeter (2nd choice for Oxford under grads), Edinburgh (Good for Comp Sci), Swansea (Good for beer), Imperial College (Good for Science), Hertfordshire ('Cos I went there)
On a similar vein as dafyd, The Times is the most highly regarded list of universities in the UK. Their top 10 for 2004 are as follows:
University of Cambridge;
University of Oxford;
Imperial College London;
London School of Economics;
University College London;
University of York;
University of Warwick;
University of Bristol;
University of Nottingham; and
University of St. Andrews.
I'd also like to point out that I got offered places in four of the above universities *gloat gloat* and I am still at another one which was 6th on the list at the time I came here (University of Sheffield).
Yeah it really has, that's the thing! You see it was 6th when I came here, then after I was here for a year, it dropped right down. Then the year after it dropped again. Then I went away for my Year Abroad and I come back for my fourth year to find that it shot back up again while I wasn't here! Let's watch it go back down again this year.