Back from its temporary disappearance from the specification, CSS
box-shadow is widely supported in all the modern browsers.
There are some browser comparison screenshots so you can see the state of support (the article is in Russian, but for the cyrillic-impaired, the CSS and images tell the story well enough, or you can deduce the sense through Google translate). It's fair to say that these are experimental, and not yet ready for production websites until browsers catch up, but they're interesting techniques.
Hat-tip to Vadim Makeev.