I have been living full time on this since I launched paid plans in May this year. My annual revenue goal was surpassed in first two months. But to be honest, I was very scared the week paid plans were launched. Thoughts of what if I don't even make equivalent to my previous salary haunted me (I had left my full time job 2 months before launching paid plans -- so my family and friends thought I was doing nothing for 2 full months). But, it has been profitable (touch wood!) and I am very happy about it. Been approached by investors a couple of times, but the revenue generated is good enough to expand the team by itself so I don't see a reason to take any outside investment.
But before getting to this point, I had toyed with numerous ideas and coded a bulky conversion optimization platform for more than a year. http://www.wingify.com/product/tour.php Showed it to patio11 and others who all said: "you know what it has to be simple". So, redone the whole thing and that's how Visual Website Optimizer came about to be.
I have been lucky to have learnt many great lessons: what to make, how to make and how to get covered in TechCrunch even if you are bootstrapped :)