I have a dual-head setup (NVidia TwinView) where the second screen is an overhead projector. I would find it extremely useful if I could just drag windows using the Workspace Switcher between my screens. This would help a lot especially at times when the projector is blanked or switched off and I would like to move some windows to be projected when switched on/unblanked.
Beware... tadaaaaa...Since yesterday windows can be dragged not only to a different workspace (without altering their relative position) but also within the workspace.
I made a modification to libwnck (the library which implements the pager and allows to manipulate windows) which implements this feature and submitted it upstream. I wonder if it is going to be committed to the next Gnome release or not... we'll see.
Anyway you you would like o use this functionality in Ubuntu 9.10 Karmic Koala, here is a link to my PPA: https://launchpad.net/~wojnicki/+archive/ppa
And if you want to compile libwnck by yourself you can find the appropriate patch at the feature request: https://bugzilla.gnome.org/show_bug.cgi?id=604207