Cloakers are just links on a page to a page with loads of other links on, I used to use one, it was working great but then it all went down hill, somehow the search engine found out I was using a cloaker and it removed over 80 of my links from the search engine, if your going to use one and your desperate be careful as they can make things worse than.

Some claoking programs are here:

http://www.phantomcloaker.com/
http://www.ultimatecloaker.com/
http://www.amazingcloaker.com/

Good look promoting your site.