Check out my guest post that I wrote about creating niche sites on topics that you are passionate about. http://www.johncow.com/create-niche-sites-about-things-you-are-passionate-about/
The problem though that I've found is when you realize that what you are completely and utterly passionate about is a very low-paying niche. Bummer! It's a good idea, but sometimes doesn't end up going over too well.
Thanks - I enjoyed your article. You really do need a lot of determination to keep cranking out new content/working on a site. If you don't have the passion that comes from being genuinely interested in a subject, it's an uphill struggle that simply gets worse over time.
I have to agree - it's "nice" to set-up sites that you enjoy being in. But "nice" doesn't pay the bill, so unless you're twelve years old and are doing it for a laugh it may not always be practical. Give me dull niches that pay $70 per lead and $10 adsense clicks any old day