I'm not an affiliate of this product, but I just bought something called of MaxBlogPress Ninja Affiliate Plugin yesterday to cloak my affiliate links for my Wordpress sites. I struggled with several other link cloakers prior to getting this, and oh my gawd what a hassle they were. This one seemed to be good based on their sales page, so I was willing to fork over quite a bit more for it than other link cloakers ($100). I'm having some problems with it (can't edit WP pages and could before and a couple other things) and their customer service seems to be silent.
Anyone know about this guy Pawan Agarwal, his product, and his site: MaxBlogPress Ninja Affiliate :: WordPress Affiliate Link Tracking Plugin