A couple more links to add:
UKIP 'watcher' site
UKIP Uncovered - by a UKIP supporter who seems to be at odds with the Party leadership (seems also to be a big supporter of the just-resigned Robert Kilroy-Silk MEP). Bills itself thus - 'What motivates the leaders of the United Kingdom Independence Party?'. This blog does not appear to have a feed, so following it will be a pain. A recent message on the blog queried whether it continues to be useful, now that RKS has quit the Party, so its continuation is not certain. The person who writes it seems also to be behind a Conservative 'watcher' site (Teetering Tories).
Conservative 'watcher' site
Teetering Tories - bills itself thus 'Conservatives! Capable of Considering Country?'. Written by the same person as behind a UKIP 'watcher' site (UKIP Uncovered), so comes at the Tories from a different angle than the other Conservative 'watcher' site (Tory Trouble) to which I already link.
(PS/ Thanks to Stuart of the Independence blog for the link to the UKIP Uncovered blog.)