The first one that sprang to mind was Sting's "Tomorrow We'll See" about a transvestite prostitute.
Brad Paisley's "Harvey Bodine" points out the "'till death do us part" clause & modern medicine make for interesting legal ramifications. "Online" is about a guy in his parents' basement and the internet.
The entire score for Sondheim's Assassins.
Annnnd this is probably too novelty, but I simply adore Moosebutter's (does the name give you a hint?) Four Shadow's Blankets and Pie.