XTorrent was for a very long time the most beautiful BitTorrent / P2P file sharing client. Although not available for download anymore, XTorrent's interface is top notch even by the standards of today - vastly better than Vuze's, uTorrent's, BitTorrent's, and even Transmission's. Beautiful times those were…
I remember buying a license many years ago; I don't recall particulars anymore, but I recall clearly that David Watanabe duped all his customers, myself included, into some sort of a financial scam. If I recall correctly, he either refused to provide the license data to customers for them to activate the software, asked payments for incremental updates - or something else along those lines.
Any any case, while his software was the best within its kind, the man's ethical norms as a developer were a total junk.