In the 'regular' version of the Sims, your sim vanished for many hours a day to go earn money. That of course wouldn't work well in the on line version! So instead, you actually perform actions to earn your sim money. These can be one-person actions, like painting a picture or whittling a wooden snome. These can also be multi-person actions, like four people getting together to use a pizza station and create pizzas.

The single player actions are usually done on equipment that is cheap enough to buy for your own home. An easel costs around $1000. On the downside, the money you make is also relatively low. You earn between $30 and $100 for each painting you make, and a painting takes about 4 minutes to paint. Note if you line up 4 or 5 easels and get lots of people painting at the same time, each person makes more money because now you're part of a "group". So it pays to work even on one-person activities near other people doing the same thing.

The multi-player activities are much more fun and also more lucrative. Four people working on a pizza machine can each rake in $100/more every minute. That adds up quickly!

The Sims Online Tips, Techniques and Walkthroughs