Changing the size of the Windows 7 taskbar

Right-click on the Taskbar, uncheck Lock the taskbar. You can increase its height by grabbing its side and dragging it up.

For the zooming effect, not possible by default, unless you replace the taskbar with an alternative dock. There are some suggestions here. LifeHacker has also a list of application docks.

OK, I did some digging...

• In the suggested question by Snark, there was a mention of Object Dock, which seems like a cool MacOS X Dock replacement for Windows. Officially it does not seem to support Windows 7, yet... But in the forums there are mentions of getting it to work.
• Then you can obviously increase the size as suggested by Snark. But I was looking for a way to shrink it. I didn't quite make that clear in my question, sorry for that.
• There is one way to shrink it a little, as it turns out: Choose small icon size.
• Another good way to get back screen real estate is to turn on Autohide. I guess that's what I will use.
• I just found another way... which might be a little extrem: Totally eliminate the taskbar.