For a while now I've been using UltraMon to give myself a taskbar on my second monitor. It also does a couple other minor tricks, but the taskbar is by far its main feature.
I recently stumbled across Actual Window Manager, which seems to fullfill the taskbar and plenty of other functionality, such as roll-up and transparent windows.
I have yet to try that second one, but it's on my to-do list.
Anyone know of any other apps for enhancement of multi-monitor Vista systems?