You're looking for an agent essentially who will be getting a portion of your earnings, though you won't be truly paying for the service the agent provided (the company will). I've written about this twice (1,2), inspired by a piece here on HN, as a potential solution for the problems in contingency recruiting, but with fees being paid by candidates. That is the key differentiator to that agent model - the job seeker, not the company, foots the bill.

Would you pay say 2-5% of your annual salary to a recruiter/agent every year? Even in years that you aren't actively looking for a job?

These are interesting questions if you think the recruiter can find you good jobs that you might not find on your own, can provide solid career advice, and negotiate salaries that are higher than what you might receive otherwise. If I can negotiate a 5% higher salary than you every time, paying me 2% every year is a pretty easy decision. Most technologists probably trust that they are as good at (or even better) negotiators than most recruiters, and in many cases they may be correct.

(1) http://jobtipsforgeeks.com/2012/09/17/disrupt/ (2) http://jobtipsforgeeks.com/2012/09/26/disruptii/