I am working on a campaign and will eventually need voice-actors and playtesters. Where should I post about this when I get far enough to do so?

Don't flame me...

UMS Mapmaking Assistance. I think.

I would say that UMS Theory and Ideas, or Map Production would be the forums you would want, most likely the latter, although, when in doubt, you can always post in Null.

I would post your campaign/map info and stuff in the Map Production forum. Then the needing of assistance of voices and testers in the UMS Mapmaking Assistance. Or you could add into the topic in the Map Production thread asking if anyone would like to help do voices and testing at the bottom of the map information.

Didn't we used to have a Team Projects forums/subforum that died of lack of activity?

Subforum, and remember IP's stance on those

Lack of Topics, or lack of finished projects? Every group mapping project I was in died due to something else happening.

If group map projects keep dieing, why don't we start one so UBERLY EPIC it has so many people in it it can't die? Like, half the people on this site kinda epic. Or maybe that would be to big and just die due to a lack of co-ordination...

Map Production, just have all of the required info and say there are slots open for testers and voice actors at the end of your post.
Hey old people, remember SeN Quilt Bound?

Thanks guys. No one post here anymore.

I'll go with fatal's suggestion.
Maybe with the release of sc2, we will have a forum where you can request help for things other than assistance with technical problems/triggers, for things such as this, graphics, music, sounds, etc.