If you spend a lot of time working with styles, this next tip is for you. And it works in both Word 2007 and Word 2010.
To view the active style and quickly change it or modify the base style, you can use the Ctrl+Shift+S shortcut to open the Apply Styles dialog box:
Best of all, you can dock this so that it's always visible (and not in your way) by dragging it to the far left or far right side of your active document:
Click Reapply to apply the active style on the dropdown list to any selected text. If you apply styles frequently, click the Styles button:
This opens a full list of your Styles, and it too can be docked by dragging it to the far left or far right:
You can also click Modify on the Apply Styles pane to edit the active style: