Helium has been paying since several years now. Helium is an interesting marketplace to linger around, browse articles and develop contacts.
They pay on articles per click plus you can make money if your content is selected. The pay has improved leaps and bounds since I joined Helium long time back. I hear now they pay $16 to well over $100.
Initially, Helium was used by freelance writers just to gain readership and to create an image for self as authors. It provided ab active platform to network.
As of now, there are about 1 million articles published in Helium.