Oliver Kamm
Politics, economics and culture from the master. Unmissable.

Daniel Finkelstein's Times Comment Central
A daily must-read. 

Tim Worstall 
Lots of interesting nibbles - and a ruthless swatter of economic gibberish.

Marginal Revolution
Tyler Cowen's riveting economic blog.

Harry's Place
Must-read left of centre blog from writers who understand the threat to the West. 

Thought Experiments
The peerless Bryan Appleyard's blog.

Opera Chic
An American in Milan, on opera.

Intermezzo
A London-based classical music enthusiast.

Jessica Duchen's classical music blog
Does what it says on the tin.

Samizdata
Libertarian blog, packed every day.

Norm's blog
The thoroughly sensible thoughts of renowned left-wing academic Norman Geras, Professor of Government at Manchester. And cricket, too.

Public Interest
Peter Briffa's inimitable take on The Yazzmonster and other assorted demons.

Reform
The public sector reform group; their website is an invaluable source of data and ideas.

Centre for the New Europe
The leading European public policy think tank.