Kevin Umback created Flysource (originally packaged as flyshare) to allow fly tyers from around the globe to be able to trade and share fly patterns in an easy to use standard file format. Basically it works the same as Napster or Limewire in that in order to find and download patterns, you need to log into a net server where other tyers are logged in. You can then see a list of available patterns and select the ones you would like to download. The software allows you to create patterns without being connected to the server, and some sites support the .fly format and allow you to download pattern files to use with the software.
To sign up and start sharing, head over to flysource.net. There is a short sign up process, but it’s quick and worth access to this resource. You can also find extra content in the download section of the site or on the forums at http://flyangler.ca and http://flyfishcalgary.com. I have some 1600 patterns in my program stored right now, and I find it to be an invaluable source of information.