I understand they are not as effective as they used to be
It seems that Google is catching on to these and is penalizing websites that are very blatant about this technique.
Most that I know of are using the Link Web. Mark Dickenson of Backlink Bully was offering a course on this, it was very comprehensive. Cost about $7.00.
I used link wheels early this year on 3 or 4 sites and they are doing well with first page placement.
I am still convinced that content is king. Build a good, informative site and you will get traffic.
DTaylor