If a big program fails to compile, it's too big to sort out. So if more than three people are going to use the project, use autoconf. It will make life easier. At the start of the project, they were all writing little programs and using an ftp server to share the code. It made diffs, change-tracking, and patches way easier.
Version control is vital with more than two developers.
Very early on, Taj wrote a perl program which mailed everyone about every CVS change. When it's still reasonably small, this is really useful because you can see how your little program fits into the overall pattern. It's also really cool to look back over the messages and see how far you've come. KDE's very complicated now it's so big. You need a channel like that for telling people what's going on, or even developers don't know what's going on.