Hey,
A reproductive hormone profile which measures oestrogen, progesterone, FSH, LH, prolactin and androgens can be useful in the diagnosis of PCOS. The major abnomalities would be a raised LH to FSH ratio (of about 3:1), raised androgens and sometimes a slighty elevated prolactin level. A glucose tolerance test is sometimes done as PCOS can be associated with insulin resistance. Don't really know of any other tests that are useful.
Hope thats some help