PM Hut once in awhile has a really good post. Working Toward Success: How to Keep the Project Afloat is one of those.
The BAD project management processes of "not planning," or "dealing with change when it arrives," or "let's let the customer tell us what we should do next and have the project emerge out of their head," is of course nonsense in most project domains.
If it's your money, your friends are the customers, you're doing the development yourself and all the other aspects of the project work, and you've got no bounds on budget, time, or functionality - then you've got the perfect "emergent" project. Ignore all those project management processes. They're a waste of time and money.
If however, there is a finite amount of money and you're not getting any more, there is a due date for the project's deliverables and they have to show up on or before that date in some usable form, a customer that would like to know how much this will cost and when you'll be done - then you probably need a plan, a process for handling change, and some way of telling the customer about how you're making progress to this plan.
You know Project Management type of things.