Every content developer and web designer often wonders if he/she can focus on one topic. Sometimes you'll want to create a site about blue widgets, but then you'll be compelled to write about marketing (and the success you had with your blue widgets). This can cause a stream of information that you're not sure where to focus your efforts. Should you talk about everything on your bluewidgets.com site, or should you break up into several other sites? What's the best solution?
On a similar note, what if you're offering a product and start expanding your offerings? Say that each product has a separate brand. Should you use your long-lasting current site and build upon it, or should you create a brand new site for each subsequent product that you develop?
Here are some proposed solutions. First, let your current rankings dictate your direction and use your existing site as leverage for your new product.
It's typically better to accumulate your links to 1 domain if you want to consider ranking well.
Consider this: there are sites that do this already. As Ruud Hein says, "If Amazon can sell books, clothes, diapers and groceries without starting a whole slew of sites than why can't we?" But that is a claim that's contested by Ron Carnell at Cre8asite Forums, who mentions the element of market segmentation. It really depends on the audience. For example, if you're selling Rolex and Timex, you probably do want to boost them on separate sites. At High Rankings forums, nethy explains:
The best option depends on the effect these desicions have on your site's conversion rates, the likelihood of aquiring natural links, customer loyalty and many other things that we cannot predict or even begin to speculate about. These desicions all indirectly affect these things depending on the micro-details of their implementation.
So ideally, this is a matter of testing and retesting to see what works.
As far as one site is concerned, some others echo that it's a better idea. With one site, you have to worry about one site to maintain. You only have to promote one site. It makes your life just a little bit easier.
At the end of the day, it's important to weigh in on a lot of factors - your time commitment, your desire, the conversions, the ability to get links, and other elements.