BiglyBT is a BitTorrent client based on Vuze (previously Azureus) which first released in 2003.
It's killer feature is integration with I2P and TOR anonymyzing networks.
They are available as plugins or can be used with your local node using SOCKS.
BiglyBT and are two torrent clients in active development
that can work on clearnet and I2P simultaneously, cross-seeding the torrents and swarm-merging them.