I personally would prefer the type ahead interface that del.icio.us uses for adding tags. That way it would be easier to quickly add several tags, but know if they are used in the project already.
It would also be nice to seperate out tags that are used in the project, and ones that at more universal. If other projects have good ideas on tags, it'd be nice to get some hints at that, especially for new projects.
I personally would prefer the type ahead interface that del.icio.us uses for adding tags. That way it would be easier to quickly add several tags, but know if they are used in the project already.
It would also be nice to seperate out tags that are used in the project, and ones that at more universal. If other projects have good ideas on tags, it'd be nice to get some hints at that, especially for new projects.