As they say "a life without regrets is a life not worth living". I don't know if you could term any of my side projects as startups but that was what was in my mind as I plugged away at them until they failed or fizzled out.

I've no regrets about building those things, I learned a lot and applied that knowledge next time round. I regret certain decisions like spending a beautiful summers weekend working on code no one would use instead of spending it with my friends and family and building something a bit more MVC. But that's how I learn so ultimately to regret it would be to constantly beat myself up.

Had the impact of those decisions been bigger maybe I'd have regrets, I don't know.