In Spaces it's possible to specify which space a given application will open on -- for example, my web browser always opens on Space 1 and iTunes on Space 3. Is something similar possible with multiple monitors, so that whichever space I'm on a certain application will always open on the second monitor? For even more control, can I specify that it will always open on Monitor 2 of Space 4?
Not with the default Apple Spaces.
There is an alternative, though. CocoaBots makes a small app called Hyperspaces which builds upon the default Spaces and adds a bunch of cool features. Multi-monitor support is coming to their next release.
Stay App sounds like it might do what you want.
If you’re fastidious about keeping your windows tidy, Stay is for you. Stay ensures that your windows are always where you want them to be, even as you connect and disconnect displays.