Conditional text is one of the compelling unique features of OOo/SO and is
helping me convince groups at my university that we should consider migrating to
OOo.  Unfortunately, its implementation is awkward and hard for most people to
find, much less understand.

Currently, conditional text is entered into a single-line text field in a dialog
box.  The user must (1) find the Fields dialog box to insert the text, (2) edit
as much conditional text as exists in the text field (not text area), and (3)
place text with arbitrary conditions in quotation marks to keep it from
mysteriously disappearing.  Conditional text also cannot contain anything
"interesting"--no graphics or other objects, and not even formatting tags.

The actual file format implements conditional text using a simple surrounding
tag, and so it seems that the most approachable way to handle conditional text
would be to provide a formatting button like Bold or Italics that instead says
"Conditional..." (perhaps with a question mark for an icon) and on selection
produces a dialog asking for the condition.  This would make editing conditional
text (and other content) significantly more convenient and usable.