Nothing wrong with what they are doing. Just a lot of keyword rich hyperlinks. Aesthetically not pretty but it works. This is a very valid and effective technique. I use it all the time in various degrees.

They are linking to there own pages as well as linking to clients pages that in turn link back to them. It's bit overboard but it's really just a hyped up version of a "site designed by" link and a "portfolio of clients list". Plus they put it below fold so you don't really have to look at if you don't want.