I am often asked how to start a freelance writing career. There are two ways. One is to cold contact companies. The other is to apply to freelance writing positions. Here are some websites that list writing jobs.
LinkedIn has a job section that features not only traditional office jobs but freelance and telecommute positions. The website allows users to create job alerts based on saved searches. You also have the ability to save specific jobs and to apply to positions using your LinkedIn profile.
The site also offers LinkedIn ProFinder that allows professionals to bid on freelance gigs. The service was free, but now is available only to those who have a premium account.