One hobby of mine is juggling. I first learned as a kid but didn't really begin to pursue it until around 2004. I'm not that good yet, but can juggle 3 clubs or 5 balls in basic patterns. Below are links to juggling websites that I find very informative or entertaining.
AnthonyGatto.com - The best "technical" juggler in the world. Lots of impressive video clips and an informative online forum.
JugglingInsanity.com - Michael Karas' website with lots of creative juggling video clips.
Wildcat Jugglers - There are some very good tutorial videos for the beginning juggler at this site.
International Jugglers' Association - A resource for jugglers.
Dube - Juggling Supplies.
Renegade Juggling - Juggling Supplies.
Serious Juggling - Juggling Supplies.
Juggling Store - Juggling Supplies.