Click to reveal fill in the blank aswer

http://word.tips.net/T000042_Adding_a_ScreenTip.html

You can use the \o switch (that's a lower-case O, not a zero) to create a tooltip, like this:

http://word.tips.net/T000657_Helpful_Popup_Screen_Tips.html

http://word.tips.net/T003779_ScreenTips_without_Hyperlinks.html

Thanks for the tip Phil.  And thank you everyone for your input.  It looks like the only three options so far are to use existing features within Word.  So far, I have not found a macro.  The three options for creating a roll-over/pop-up box effect so far are:

1.  Comments

2.  Endnotes

3.  Hyperlinks in combination with it's Screen Tips feature

For anyone who is interested in this subject, below is my analysis of the three options along with the advantages and disadvantages of using each option for creating a roll-over/pop-up box effect:

You can create the pop-up box effect by creating a comment.

Advantages:

You can hide any of the symbols and property text associated with comments.  For example, the comment reference mark (e.g., [jb1]) will not display unless the user has the hidden text box checkmarked within MS Word.  You can also eliminate the User Information that displays within the comment pop-up box by deleting the User Information within the Options box prior to creating the comment. 

Disadvantages: 

I don't think you can eliminate the red highlighting from the text within the body of the document to which the comment is referring.  Also, the reader can open up the comment pane, which exposes the source of the pop-up boxes. 

You can create the pop-up box effect by creating an endnote.

Advantages:

There is no highlighting, and there is no user information associated with the pop-up box.  Also, the user can not reach the endnote pane (similar to the comment pane) without switching from the Print view to the Normal view.

Disadvantages:

There is an endnote reference mark, which appears as a superscript, and you have a corresponding list of endnotes at the end of your document (although you can insert a series of page breaks so that the endnotes do not appear right after the document body).

You can create the pop-up box effect by creating a hyperlink that includes a screen tip connected to a bookmark.

Advantages:

There is no highlighting, there is no user information, there is no reference mark, and there is no corresponding pane of text like there is with a comment or an endnote.

Disadvantages: 

The number of characters that can be entered into the Screen Tip dialog box is limited and, therefore, the number of words within the resulting pop-up box is limited.

Justin Baker