I've just come across a very useful write-up on building niche minisites. It is targeted rather at newbies, but is quite in-depth nevertheless and covers many aspects of this process, like:
- finding and researching a niche
- deciding on method of monetization
- designing the site and generating SEO-friendly content
- placing ads
- hosting
- link building
If one of your new year's resolutions was to build a niche empire, that may be a good place to start with.
