For me it's around $1600-$1800/month https://itunes.apple.com/us/artist/cobbysoft-media-inc./id40... A portfolio of paid apps. Most of them were created to scratch my own itches. I was learning saxophone at the time and couldn't really find a fingering chart software that can play the exact notes and vice versa. One thing lead to another, that's how it all began.

http://www.optimalplugins.com/ Branching out to wordpress plugins. Speaking of which, I think the headline generator is a really awesome plugin for any blogger. Just need some help to scale the marketing part.

http://www.stickynotespro.com/ A tiny SaaS working in progress :). My mind is always coming up with ideas and I usually write them down in sticky notes or in the note app. However, being a visual person, I need to see the post it to make things happen. If some one cover the sticky notes with a blanket, the task will never get done. Creating this site to store big ideas digitally and have the ability to see all the sticky notes on demand.