Twitter recently adjusted its terms of service to allow advertising on the free micro-blogging site that rakes in some 45 million visitors each month.

It should come as no surprise that the creators are looking for ways to make money off the site's mind blowing success. Nielsen Online numbers showed this year that Twitter saw a growth of 1,382% year-over-year February 2008 to 2009. Pretty impressive.

What will ads on Twitter mean for users? For one thing, it will keep the service free. As for the actual integration of the ads into the content... Twitter said in its blog that "traditional web banner advertising isn't interesting" and that they are going to "leave the door open for exploration in this area."