IMDB Age is a Greasemonkey script that I wrote. This script calculates and adds the age of an actor or actress, their Tropical Zodiac Sign and their Chinese Zodiac Sign on their IMDB page as well as how old they were when they stared in each performance. It also adds how long ago a film was made.
I have a few screen shots so you can see what it looks like.
It was was created on 2005-03-29 but inspired sometime in 2001 and the last modification was on 2007-08-21. And the current version is v2.2. First you need Greasemonkey installed then install the script. It is available locally or on the userscripts server.