[markrickert]

I've built a successful side business (http://www.mohawkapps.com) and was even featured in an e-book: http://www.sideprojectbook.com/ - by creating iPhone apps for niche markets and marketing heavily to them through facebook and in-person tradeshows. I gross about $2k-$4k a month but I haven't quit my day job yet.

Apple does a lot of my marketing for me but I also rely heavily on word of mouth. I make sure to have a screen in all my apps that allow users to tell their friends through texting and email about the app. I'm also an apple affiliate so all the traffic that goes to the app store through my site nets me another 7% of all that user's purchases during the session... it makes up for the gigantic chunk of change that Apple takes from my sales.

Recently, I've started branching out into more generic apps that are useful to a wider market, but my niche apps make way more money than the broad-audience apps.