Do you mean companies which sells articles in upfront payments?
There are A LOT of those. Type in article writing service in Google.
No, companies that purchase articles written by me, companies such as the old associatedcontent.com
Problem is, I'm not a US citizen, and although there are some methods of fooling them, I have found that since associatedcontent has been purchased by yahoo, I get my accounts flagged more often than not.
if that's the case your best bet might be to go independent and offer your article writing services through the freelance sites or your own marketing
Textbroker pays every Friday now, which should be close enough to be considered upfront. You should sign up, try qualify for level 4 (at least 3), and complete at least $10 worth of articles by Tuesday. After a day or two they should be accepted, so you can request payment on Thursday to receive money by Friday.