Gnash, the free software Flash player
Although Gnash handles many popular sites and media (such as YouTube), much work is needed to be a full replacement for Adobe's Flash player. Visit http://www.gnu.org/software/gnash/ for more details about installing and using Gnash.
Ways to help. The easiest way to start helping the Gnash project is to use the program and to file bug reports. If you want to find out how to become a contributor to the Gnash project, consider joining the Gnash developers mailing list (firstname.lastname@example.org), the Gnash discussion mailing list (email@example.com), or dropping by #gnash channel on irc.freenode.net.