Workspaces are invaluable in keeping focus on the job at hand. I've been used to Workspaces on Linux Desktops for a long time, and recently discovered a Windows powertoy - MSDVM - that does the same on windows. This idea is a couple that I've had that can make them more effective:

• A per-workspace todo list: So that when you form a plan of what to do in that WS, the plan is visible always
• A "Send todos to workspace X" feature: I frequently find myself remembering to do something official while I'm on my personal workspace. It would be nice to be able to send a todo to that todolist without losing context.
• An "I'm stepping out" button with tickler for when you return : Click on the I'm stepping away shoudl allow you to enter quick text on what you're currently doing, so you have a high visibility "This is what I was doing before I stepped away" note on the workspace when you return. I constantly find myself doing this using a new notepad instance even though i have other todo lists - just so its front and center when I return. It would be nice if the workspace did it for me.

Of course, all of this can be done with current software and some manual setup, but it would be nice if the todo lists were workspace-aware, so this works out of the box.