Word Clock is a typographic screensaver for Mac OS X. It displays a fixed list of all numbers and words sufficient to express any possible date and time as a sentence. Word Clock displays time by highlighting appropriate words as each second passes.

[ZIP] Download Word Clock Screensaver (Mac Universal Binary)

Beta versioncontaining some bug fixes, but maybe some new ones:
[ZIP] Beta Download (Mac Universal Binary)

(via Simon Heys)