Sending an email to webmasters asking for a link to your web site is also an option to gain more incoming links. But sending an email with text such as the following will not get you a link from my site.
Hello,
I have found your web site really informative and I think that my web site http://www.example.com could also be of benefit to your visitors.
Please consider placing a link on your web site and send me the page with that link and I will link back to you.
With kind regards,
Webmaster of http://www.example.com
So, what is wrong with such a request. You don't use the name of the webmaster or company involved. You don't show that you really visited the site and read some articles. You don't talk about the topics and benefits that visitors might find on your site. You request a link back before you consider placing the site link on your site (a dead give away of non-relevance, otherwise you would have linked to the site already).
You ask for a confirmation...