It looks like the LDS (aka Mormons) have implemented online microfilm rentals. My local Family History Center told me about this feature back in the Fall of 2010 — so I have been waiting. It is only on the West Coast now … here’s the news from About.com:
Can anyone tell me when it will be available on the East Coast? I recommend using the LDS microfilms before heading to Poland. You need to train yourself on the paleography of the older handwriting and languages involved. The old Cyrillic (pre-1918 reforms) is enough different that expert Russian Language speakers struggle because they have not see all of the characters that used to exist.