My admittedly brief search for a page that shows orphans didn't turn up anything that was useful, so I'm hoping someone has one. It seems a valuable resource for anyone involved in a trade where one side claims that the payment was confirmed and the other disagrees.
If you're looking for an absolute authoritative source that will show you latest orphaned blocks, its impossible and anyone that claims otherwise is scamming you.
The Bitcoin network is a fully decentralized peer-to-peer network, therefore in the event of a temporal split (i.e. two blocks of the same height racing in the network), a block-tip that was accepted to extend the canonical chain will not relayed to adjacent peers (though it it is stored locally for record-keeping purposes). In that sense, it is only natural that no one can tell with absolute certainty of the existence/or the non-existence of the latest orphaned blocks.
You can increase your likelihood of capturing all orphaned blocks by sampling across more nodes that you personally run. But the only way for you to get the them with absolute certainty is for you to own the entire network -- which is impossible.