I've been juggling for a few years now and find it both useful for zoning out and thinking about tough problems, and intrinsically satisfying - it's a great feeling to nail a new trick for the first time.

For anyone interested in learning I found this video site extremely helpful:

http://homepage.mac.com/abramr/juggling/tutorial/category/in...

Takes you from complete beginner to covering loads of 3 ball tricks, and onto 4 and 5 ball if you are so inclined. Has side by side full speed and slow motion videos.

The mathematical structure behind juggling patterns is quite interesting - various notations have been developed including siteswap:

http://en.wikipedia.org/wiki/Siteswap

A guy at party who was totally off his face on amphetamine told me this while juggle 3 balls. He said the skill synchronously activated both left and right side of his brain. He was defo on the right lines and since inspired me juggle too.

Not to discount this specific tidbit, but perhaps as a rule, it's not the best practice to hold the wisdom of someone in this state in high regard. On the other hand, there seems to be a propensity for humans to do so, dating back to the Oracle of Delphi, so you are in good company it seems.

Juggling was recommended to me by a physio because I was getting shooting pains in my wrists. I used this to learn:

http://video.google.com/videoplay?docid=-6366713757585864298...

I find it rather good for thinking about bugs, as it's totally automatic once you get the hang of it.

Learning new things (mills mess at the moment) is great for coding productivity too. I can only handle dropping things every 10 seconds for about five minutes before giving up on procrastination and getting back to work.

Different report here:

http://news.bbc.co.uk/1/hi/health/8297764.stm

I prefer it to the one in New Scientist - YMMV.

I juggle and think it has loads of benefits. It's nice to see some concrete evidence.

A previous item about juggling affecting the brain's structure:

http://www.medicalnewstoday.com/articles/5615.php

I became very curious about juggling when I was younger, so one afternoon I started learning how to juggle 3 balls, using some oranges and an animated .gif.

My fascination with juggling only lasted for about a year, during which I learned how to juggle 3 and 4 balls (still can't do 5), flowersticks/devilsticks, diabolos and poi. I remember that learning each one got successively easier.

That being said, I'm not a particularly good juggler. Learning just the basics of each juggling prop and maybe a couple of tricks, was enough to satisfy my curiosity.

I like keeping a set of soft juggling balls around. You can squish them, play with them and throw them at people. Getting up from my chair and juggling for a few minutes really helps reduce the strain on my eyes, back, wrists and mind. I also do some of my best thinking during those minutes.

I'd recommend juggling to any hackers that spent a lot of time in front of a monitor.