Staffing Agencies will find you jobs

Typically an employer pays the staffing agency $2 for every $1 that you receive. However the staffing agency doesn't keep the difference, entirely.  Unless you are a true independent contractor, they withhold your taxes for you, pay workmans' compensation insurance, and 401k (if you qualify).

B E W A R E :
Exclusivity agreements are typical, in which you must agree not to take any other job through any other staffing agency.  If your staffing agency places you in a part-time or temporary position with a company, you will have to pay the agency if you take a full time job with that  employer. Sometimes, you have to agree that if you take any job while on the agency's roster, you owe them a percentage of your salary. Most of these agreements only stay in effect for a few months or a year.

Most "contract" job through these agencies are temporary but some can turn into permanent jobs. 

Qualifying as an independent contractor
1099 or W2?  It's complicated

Tips for Using Staffing Firms

AGENCIES
Creative Circle Advertising + Creative Staffing

http://www.synergishr.com/jobs/creative-jobs/

Aquent Staffing

Sherra Bell / Consult Sherra

Vitamin T Staffing

iCreatives Staffing

Northrop Grumman (usually placements within government)