Usually link exchange companies do this but it's been my experience that all I get is fluff from these sites, i.e., non related businesses wanting to trade links, i.e., casinos, etc.
There is no easy way to gather links. It's hard work. But when its in your control you can do a lot better job of finding quality links than with any other method.
There is one site that allows you to search for a keyword and it brings back sites according to page rank.
I usually search for a keyword and the word "link" and then it often brings up a page where the link will appear, saving time.
Also search for "getting good backlinks" for other ideas.
[edited by: martinibuster at 5:42 pm (utc) on July 21, 2005]
[edit reason] spelling [/edit]