BitSpirit is a very powerful and easy-to-use BitTorrent client that provides not only full BitTorrent protocol implementation but also many personalization features.
BitSpirit supports simultaneous downloads, download queue, UPNP port-maping, NAT traversal(UDP transport), select downloads from multiple files torrent package, disk cache, chatting with other peers, torrent market, ip-filter, etc. In 3.0 or above versions of BitSpirit, it also supports DHT network – which is based on Kademlia protocol – and fully compatible with Bittorrent official client.