Someone who creates web pages that are either full of links to junk, or full of links to other links to other links. Link farmers harvest popular search engine terms from search engines such as "free games" or "free ebooks" and include these search terms in their link farm. However, the page never has any actual content relevant to the search term. A link farmer is a more passive form of emailspammer, but uses junk web pages instead of junk email.
Link farmers are an Internet lifeform that are just as bad as email spammers.
link farms are web pages that either have many links to crap or links to other links to other links. Link farms are a passive form of spam, and usually contain a search phrase that you've entered into a search engine but have no actual content.
I did a search for "free games" and generated a ton of page hits to link farms.