My favorite is probably in WP mass pull speed runs.

(Cleric Stance) Holy -> Swiftcast -> Holy -> Drop CS during GCD if necessary to resume heals. It's impressive burst aoe.

Sometimes I will swiftcast a stoneskin when I know a big hit is coming (Everybody's Grudge, MB, etc) so I can push healing or dps a little longer beforehand.

I've done it a couple times with medica, for instance if Titan tumults immediately before one of his unavoidable aoes.

I can't say I've ever seen a situation where a swiftcast cure is ever necessary. Unless you count trolling FC tanks on speed runs for the lols