But when your project is young, there should only be one channel, with everyone talking together.
Freenode gives you the control you need to administer your project's IRC channels, while sparing you the not-insignificant trouble of maintaining an IRC server yourself. The most obvious choice is the name of your project—if that's available at Freenode, then use it.
If not, try to choose something as close to your project's name, and as easy to remember, as possible.
You can also configure a bot to watch your project's version control repository and broadcast commit activity to the relevant IRC channels.
Though of somewhat less technical utility than commit emails, since observers might or might not be around when a commit notice pops up in IRC, this technique is of immense utility.
It's generally the only place where developers can meet in a shared space for real-time conversation on a regular basis. It's not hard; although there isn't space in this book for an IRC primer, is a good guide to IRC usage and administration, and in particular see the tutorial at irchelp.org/irchelp/