I think people management is intrinsic part of any director's profile. However, sometimes, you like to do certain things yourself (lack of budget, complicated idea that language cannot explain) and so here are some very useful apps that I think will help up maximize productivity.
1) Storyboard Software:
A picture is worth a 1000 words. And if you have to communicate a shot to your DOP, actor, production designer, AD, it is sometimes worth 4000 words.
Here is a very handy and useful app for storyboarding: http://tamajii.com/storyboards/
They also have storyboard in 3D: http://tamajii.com/storyboards3d/
3) Photoshop http://itunes.apple.com/in/app/id495716481?mt=8
Working on photoshop - making those posters could be easier with this app. I haven't tried it out and some feedback is that it is not very smooth (first version maybe). But I think it will make it more intuitive with time :).