I recently found out about the Elbereth engraving through the NetHack wiki. Are there any other "special" uses for engraving aside from this one?
Of course! Engraving is one of the most reliable ways to identify wands. See this page from the wiki on how to use engraving to identify your wands.
A little usage advice: First, engrave (with your fingers f.ex.) a normal Elbereth, because some wands like polymorph are only identified, when you engrave somewhere where you have something else engraved already. Second, also when engraving with the wands, write an Elbereth. Never engrave any other text, because 1) Elbereth is always good to have and 2) writing Elbereth as opposed to anything else improves your Wisdom stat.