To follow up on this, the PayPal options aren't really helpful. There is no "review" option, only accept, accept and report, or deny. The first two do nothing to stop fraud, and the third stops legitimate buyers, too. So, PayPal's no help there.
As for using a third party service, that makes this generally more complicated than I need it to be. I don't deal with fraud very often, so I prefer an option that allows me to filter transactions based on IP location, should the need arise.
Lastly, I obviously use the block buyers/transactions option, but that does no good. If a buyer is savvy enough to use a proxy to hide their IP address (as mentioned above as a reason IP blocking wouldn't work), then they are QUITE savvy enough to constantly be changing email addresses they use to conduct their fraud. That would make the process way too REactive, as it is now, which does nothing. I need to be PROactive in my abilities to stop fraud.
As I stated before, I think IP address blocking would be helpful because it would allow the transaction to still take place via PayPal, I would find out from eJunkie it had been blocked, and that would allow me to manually view these transactions and either issue a refund if I don't trust, or manually send a code if I know they are legitimate. In this way, I am able to block questionable sales, but not block trusted buyers.
I would like to point out, I would be more than happy to pay for this option (especially if I had a whole host of fraud options) should it become available. I do recognize the value I get in my low monthly fee with eJunkie, and would be willing to pay a bit more to help my business in the long-run.