Sometimes a recruiter can provide you access to lots of work you won't find advertised anywhere on the net.
Stick your email address into our notification box on http://hackerjobs.co.uk if you want to be informed of a new site that aims to circumvent Tech Recruiters and significantly improve the recruitment process. It's not affiliated to any recruitment company so don't worry. It's a side project myself and a fellow HN'er are working on.