Joel Gascoigne proposes a method for working on a startup while busy doing something else (a full-time job to pay the bills, for example). He doesn't mention too many details of actual method, but one of his methods seems to be to do something every day to push the startup forward, no matter how small.
This is definitely a good method to build your startup if you have no other choices (which is the case for most), and I agree with Joel that it is better than his previously described "working in waves" method.
However, he is too quick to discard the potential for losing to faster competition:
On top of that, let yourself succumb to the myth that you can be killed by your competition and you’re in for a tough ride.
This really depends on what kind of product you're building. It's sound advice only in the sense that if you're building a winner-takes-all, high profile product, you shouldn't be bootstrapping anyway.