Many people will refuse to give a reciprocal link to any web site that isnt directly related to theirs. This is largely based on a misconception about the relative value of links. There are several problems with the theory, and you need to think about them before deciding whether to refuse all links.

First, many pages organize their links into a directory. Even if you accept that relevant links are the only ones worth having, a site that is wholly unrelated to yours can manufacture relevance by putting your link on a page with a bunch of similar pages. If all of the links contain a description, they will make the page contain content that is similar to yours.

Second, relevance is mainly a theory about where the search engines will go in the future. Right now, all links have some value. Regardless of what search engines will do in five years, it cant hurt you to have links that arent relevant to your page. If the algorithm changes, you can simply remove the reciprocal links to all non-relevant pages.

Third, anyone who does a cursory review of which web sites are at the top of the results will see that many have arrived there simply by linking to anyone and everyone. The search engines use different algorithms, and you can clearly get benefits from good anchor text and description even on sites that have nothing to do with yours. Just avoid reciprocal linking with so-called bad neighborhoods such as gambling, adult, and drug sites.