What are link farms? Are the following URLs link farms?

Being new to SEO, I read SEO for Dummies and it mentioned that Link Farms are pretty much worthless.

However, I'm not so sure what the definition of a link farm is?

I downloaded this program called Website Submitter, which has a list of over 4500 places to have your site linked to (Mainly with a recripical link). And the program helps to speed up the time it takes to do the manual labour :

777media.com
a-free-directory.info
a-web-directory.info
a1dir.com
a1directory.be
a1webdirectory.com
a2adir.info
a2zdir.org
aaawebdirectory.com
aardvark.co.za


Still it takes me about an hour to fill out 50 links. And maybe 50% of them are free. However, I'm not so sure if these websites are Link farms.

It seems allot of them have a similar designers as their email confirmations look identical. So I'm guess one person massed produced these sites and just gave them different domain names. I've posted the a few of the links below and wanted to know if they constitute a link farm?

Also, is link farming as useless as they say? Because with 50 links per hour, 3500 links would still take me 70 hours of work. A substantial amount of time.