I quit my job about 19 months ago and had the luck to get immediately re-hired by my former employer as a freelancer for a few months on a much higher rate (http://steveridout.com/2012/12/30/a-welcome-delay.html). This, combined with living in Madrid now instead of London, has given me enough runway to live cheaply for another 2 years if needed.
I've been working on my current SAAS project http://readlang.com for 11 months now and despite showing a lot of promise it's still not even ramen profitable. I'm still feeling very hopeful about it though and while it's looking promising have every intention to follow through to see where it leads. May write a blog post about this as it approaches it's 1st birthday.
I'd say your 6 months is on the short side for creating and selling a product of your own, and would recommend you try to find consulting gigs to save up some more money first if this is the road you're considering. If you just meander and hop between a bunch of projects for a few months I fear that in 5 months time you'll be looking to take for a normal job again, perhaps running back to your old company! (I've actually done this before - I took a year off with no plan, didn't focus on a project, and ended up re-joining the same job I'd left.)
Anyway, good luck, look forward to see what you can create!