Including EF I review for 13 companies. I won't list here because I am not giving ad space to them on EF's page.
I review on my blog and have the traffic to support it. There are a few places that I'd **love** to review for but haven't gotten the opportunity to YET.
Getting started, I'd say start up a blog and start writing. Market it well (advertise advertise advertise!) and you will get readers. Advertise yourself on here, on twitter, get yourself into the blogging world (comment on other people's blogs and they will come to yours), and participate in elust. Those are all great ways to get traffic. After you get a small following, contact companies. Most are happy and willing to work with you if you have prior reviewing experience.
Hope that helps. If you have any more questions, feel free to private message me.