Gymnastics

[cletomex]

I've been doing some gymnastics training for the past year. It is hard as hell but definitely builds strength

GSP loves it
http://sports.yahoo.com/elite-athlete-w ... d=26492558

[Scrap]

Best Sports Strength conditioning there is, leaves weights for Dead.

[EddieShredder]

Couple of lads I know swear by it... one does it for BJJ, and one for Parkour...

[Deserter]

I think it's awesome and it doesn't just build strength, it's beneficial in terms of developing flexibiilty and agility as well. Most people just steer clear of it because it's so challenging.