I'd second this, especially as a temporary measure. You'll of course have to be prepared to be fired outright, but odds are if you offer to stay on a while and

I'd second this, especially as a temporary measure. You'll of course have to be prepared to be fired outright, but odds are if you offer to stay on a while and help them hire and train a replacement, they'll take you up on it and you'll leave with all your social karma intact - which means you may be able to come back later if your startups go belly-up. Social karma has real value that way, it's worth some effort to maintain.