USB Loader project, based on WiiFlow 1.1 by Hibernatus, Wiiflow 2.1 by r-win and Miigotu, and Wiiflow 3.0 alpha by Miigotu.
Links:
Source
WiiFloWiki (For downloads and mostly up to date information on usage)
The IRC Channel (irc.abjects.net #wiiflow-advanced)
Thread for Wiiflow 1.1 - 3.0a...