The overall quality of your inbound links--no matter where they're from--is more important than the quantity. A glut of irrelevant, spammy or otherwise low quality links will actually do more harm than good. So if you're thinking of going the microsite route, be sure to start with a solid strategy.
Ask yourself how the sites will benefit your target audience, how many there will be, and most importantly--whether you're just building them to obtain links. "Don't just build sites for the purpose of linking," Nimetz says. "Ensure that the sites provide value to the user."