aria2 is a utility for downloading files. The supported protocols are HTTP(S), FTP, BitTorrent, and Metalink. It has a powerful segmented downloading ability, downloading a file from multiple sources and multiple protocols and utilizing your download bandwidth to the maximum. It supports downloading a file from HTTP(S)/FTP and BitTorrent at the same time, while the data downloaded from HTTP(S)/FTP is uploaded to the BitTorrent swarm. Using Metalink's chunk checksums, aria2 automatically validates chunks of data while downloading a file like BitTorrent.
Soulseek (http://www.slsknet.org) is a communication and file-sharing system. It is quite similar to Napster: it lets you exchange files, search for files, chat with other users in public and in private, browse their files, and get recommendations for music. SoulSeek for Linux is a GUI client for the system written in Python/wxPython. It includes all the major functionality: chat, searches, and file transfers.
Sharity mounts shares exported by Windows, Samba, and other SMB/CIFS servers in the file system of Unix computers. It implements Resource Browsing, which is similar to the Windows Network Neighborhood (Netbios Workgroups and Active Directory), NTLM, NTLMv2, and Kerberos authentication, Microsoft's Distributed File System (DFS), and manipulation of Access Control Lists (ACLs).