Careerbuilder is definitely legit. I have used them before and have gotten interviews through them.
A few others:
www.monster.com (I got my third most recent job through them)
www.dice.com (for techies such as m'self; I got my last 2 jobs through them)
www.truecareers.com (for college grads only; you need not be a recent grad)
I
strongly advise not splitting your focus, and only looking at a few such sites for general stuff, and also target specific companies where you'd like to get work and go directly to their own websites. E. g. I realize this does not specifically apply to you, but if you wanted to work at, say, Apple Computers, it would pay to also look at Apple's own website and check out their career/job postings.
Another thing I advise is to follow whatever is offered by the state. Massachusetts has a rather good online system now (they didn't used to).
Massachusetts (Job Quest, click on Internet Search Tool):
https://web.detma.org/Jobseeker/CM1.ASP
For New York (Department of Labor):
http://www.labor.state.ny.us/careerservices/CareerServicesIndex.shtm
I found my most recent 3 jobs online. My job search times ranged from about a month to almost 3 years. In part, that depended upon what I was doing in the search, but it also depended upon the economy and the demand for what I do, so it wasn't just due to the online thing. I had the best success doing what I suggested above:
- focus on only a few general job search websites, and make those the big ones. Be as detailed as possible re what you want.
- Concentrate on a few specific companies you want to work for, and follow their online postings as well and
- Use the state's resources
Happy job hunting!