Seed is possibly a content production site similar to Demand Studios and Associated Content, but some "jobs" posted do offer an upfront payment.
A great list kept fairly up to date. Be sure to read this review (below) to find some time saving tips on getting the best jobs.
This board features all kinds of telecommuting jobs- it's one of the places to go when you are frustrated by all the "freelance" jobs that are locale-based.
A magazine-focused site with some freelance magazine positions in editorial. At times, regular freelance writing/remote jobs and gigs are posted.
WAHM.com lists remote/telecommute jobs from Craigslist. You'll find all kinds of jobs here, not solely freelance writing jobs.
Write Jobs is a combination of full time and project/freelance jobs, with additions popping up about once per week. Read the review below for more on the opportunites at Write Jobs.
A hidden treasure- remember, the more traffic it gets, the more competition you have.
This is a board-based listing with fairly good leads.