Decorative Text Underline uses a combination of
box-shadowandtext-shadowto form a modest underline that preserves the element color and weaves between text descenders.
Neat, yet very intensive and only works with text that is rendered onto a fixed background color (no gradients or images!). I sure do hope we can get this natively – without any hacks or sorcery – in browsers (and operating systems, in general) soon.