What are some alternatives?
When comparing MLDonkey and FrostWire, you can also consider the following products
eMule - eMule is a free peer-to-peer file sharing application for Microsoft Windows.
qBittorrent - Lightweight and open source torrent client that runs on all major platforms.
aMule - aMule - the all-platform P2P client!
Transmission - Transmission has the features you expect in a BitTorrent client: encryption, a web-based interface...
Soulseek - Soulseek® is a unique ad-free, spyware free, and just plain free file sharing application.
Deluge - Deluge is a full-featured BitTorrent client for Linux, Unix and Windows.