08-04-2006, 04:04 AM
Really depends with what your goals are. I will use a sub-domain to market a second site as a part of a bigger site, but if it is part of the core site, then I will put it in a folder. If I have forums, for example, I would normally put them in a folder. I just set up a blog on a site, though, and I made it a sub-domain as it is really a marketing tool for the main site and will be marketed on its own.