Wikipedia's take on the Rubaiyat, with links to a number of authors I have yet to find in print

OK On Life
Very artistic take on the Rubaiyat that breaks it up into manageable bite-sized chunks for the reader. For each quatrain this site provides a facsimile of the actual Persian script, a literal translation, meaning, Fitzgerald's translation, and a German language translation for each quatrain

Parody: Bridge
An illustrated parody of the Rubaiyat by a lady fond of the card game of bridge

Parody: Kittens
An illustrated parody of the Rubaiyat from the perspective of Persian kittens. Cute actually

The Keeper
Site about the movie The Keeper: The Legend of Omar Khayyam. Who knew they made a movie about it? Trailer looks very interesting

Cubic Solution
Short mathematical paper on Omar Khayyam's geometric solution of the cubic

Arabian Nights
Electronic Literature Foundation's presentation of several translations of the Rubaiyat in user-definable formats

The Persian Poet
Incredible visual interface for Fitzgerald's translation