I don't quite understand their concept. Would appreciate it if someone was to explain it. Anyone has any experience with them?

http://www.efreeservers.com/company.htm

Yes, our servers are really FREE. Whether your company requires 5 or 500 servers, the price is still exactly $0.00. Simply select EFS Networks as your bandwidth provider and your server(s) will be shipped to you at no cost*.

From there quote;

"Simply select EFS Networks as your bandwidth provider and your server(s) will be shipped to you at no cost*"

The little atserk at the end is for when you sign the 2 year contract at $300 a month for 200gb bandwidth for 2 years. If you cancel before 2 years you have to pay the balance for the server.
There concept (or at least my take on it) is that they are getting there bandwidth much cheaper than $.70 cents a gigabyte, meaning the more bandwidth they sell above that number is profit.
but on the bad side the servers after 2yrs are old and outdated, so yes you get a free old and outdated server.

But its still a good deal (at least I think so), if you burn alot of bandwidth and need alot of machines...

My $.02

Yeah, you do get your server after 20 months, but why is that any different from any other dedicated server?

Wouldn't it be wise to use your server for as long as it is worth something? I'd say 20 months is a good time to retire a server. After a year, your server becomes obsolete, just like any other dedicated server.

I think you get the idea.