OpenWrt includes many packages for sharing files.
Some Projects use OpenWrt to make filesharing easier: PirateBox.cc.
Files can be shared on the local network by using traditional methods like NFS, Samba (SMB/SMB2/CIFS) or other network file systems. Sharing via simple HTTP server or webdav (davfs2). Sharing can be done via installing FTP server overview or ::
Bittorrent Clients: rtorrent , transmission can run as a daemon.
Setting up DC/ADC servers is supported. dc.overview
:: Bluetooth supports file transfer via OBEX.