I'm going to take issue with one of the companies on his list, Riviera Partners. I worked with this company for several months last summer (Hey Matt!) and, in my dealings with them, they were utterly professional. I hate recruiters in general, but the guys at Riviera were the definite exception.

First, their list of clients were very top-notch. I did a number of phone screens and on-site interviews with companies I was introduced to via them. Never found exactly what I was looking for, but met lots of cool people and companies.

Matt was my main contact after I asked to only deal with one of their people. Was always professional and helpful. I've had good interactions with some of their other employees too.