Excellent site with lots of patterns, information on the history and traditions of Temari, help on learning, general reference information on making them, photos of Temari, lots of resources, and many other opportunities to share in and enjoy the craft.
Barbara Suess' temari site. Instructions, history, supplies
TemariChallenge is a group of experienced temari stitchers who help each other create new designs, adapt existing designs in other crafts to temari and figure out designs seen in books, websites and other venues.
The art of making Japanese thread balls; many examples and some tips.