This is similar to the function performed by Google toolbar wherein you search for a topic, navigate to a matching page and clicking on the google toolbar highlight button adds a yellow highlight to all the instances of the search text that appear in the page.

Similarly in Word 2007 a feature called Reading Highlight does almost the same. Here’s how you use it:

1. Select Home -> Find to display the Find tab of the Find and Replace dialog box.
2. Type the text you want to highlight in the Find What text box.
3. Click Reading Highlight and then click Highlight All. Word applies a highlight to every instance of the text in the document and tells you the number of items it highlighted.
4. To clear the highlights, click Reading Highlight and then click Clear Highlighting.