Hi Gunjan,
I'm sure there are a slew of these sorts of sites on the Web. RentaCoder is the best known one. I would simply Google for some. I bet that some of them are even advertising via Google Adwords.
I'm not sure what sort of work you are looking for, but the bad thing about getting work this way is that it is extremely price competitive. From my experience, most of the work is good, but it is all about the "quick and dirty" and little goes into design, testing, and architecture. Of course, companies really serious about their software projects won't take this avenue anyway so it's not usually an issue. If the company is actually serious, they usually have no clue about the software business in the first place.
You won't be getting great money from there since many, if not most, of the people there are out of the United States competing for bids (e.g., Russians, Indians, etc.). But, of course, the money thing is relative. A $200USD project means much more, and goes a much longer way, than it does in the United States compared to most of the world. $200 is like grocies in the US for a few weeks.
Another thing to note is that many companies/businesses on there are sometimes really cheap. For example, I saw a business advertise a max bid of $20USD or $30USD for a company logo. I can't imagine good quality coming out from that unless the person used some sort of template. And if the person that won the bid used a template program, then what's the point of the logo?
The firm that I work for is taking the quality approach and is slowly progressing to achieve SEI CMM Level 5.