Downloadable webfonts are not just about replacing Verdana with a fancy freeware font.
Here is an example where a certain text phrase is automatically replaced with a scalable vector glyph from a downloadable font. The underlying text stays untouched, so indexing and copy&paste work like a charm.

See the full article here: http://opentype.info/blog/2008/05/14/exploring-webfont-possibilities/

Edit: changed “graphic” to “glyph”