Winster.com
This is FREE to join! Choose from 10 different games to play. I like the slots. I am currently playing for a digital camera that I hear is just fantastic, but at xmas I used my points to get Amazon gift cards, and bought my son's some nice gifts, so I'm starting over.
They offer a day pass for only 99 cents, you can purchase items from the gift shop, and let's not forget make some Awesome new friends.
Moola.com (This link takes you away from site so bookmark now)
This one is also FREE but a bit complicated, so take your time. They give you your first penny to play one of the games, if you lose they give you another penny, you never go broke. Read the site as it explains how the win/lose percentages are split between your playing account and your savings account. As you become familiar with the site you will see it's potential.
WorldWinner.com (No link here as there is no referral)
You must join this through Inboxdollars to earn from playing unless you make cash deposits and win games. To earn as a FREE member I play through Inboxdollars.