This is from the stanfard urology site.... (yes I was board but this idea could open a whole new can of worms........)
BLUE / GREEN
Blue or green urine may be caused by a blue dye such as methylene blue, a component in several medications (Trac Tabs, Urised, Uroblue) used to reduce symptoms of bladder inflammation or irritation (1,6). Administration of the dye, indigo carmine, turns the urine green and can last for several days if renal function is poor. While more often reported to cause pink urine, the anesthetic, propofol, has also been reported to cause green coloration of the urine (11). Amitriptyline, indomethacin, resorcinol, triamterine, cimetidine, phenergan, and several multivitamins also lend a blue-green tint to the urine (6). An inherited form of high calcium (called "familial hypercalcemia") can result in blue urine, which has lent this disease the nickname "blue diaper syndrome" (12). Another metabolic disorder, indicanuria, can cause blue urine due to tryptophan indole metabolites (12).
A blue pigment may also be produced by infection with the bacteria Pseudomonas (1,2). Dark green pigmentation, especially if associated with air (known as "pneumaturia"), urinary tract infection, and/or solid particles in the urine, can be caused by bile when there is a fistula between the urinary tract the intestines.