For doing or watching? skiing where they jump off cliffs is awe inspiring but I'd never be able to do it. technically bmx racing is an extreme sport so I can tick that box and I race mountain bikes so that probably counts.
Skateboarding Big Air. Look it up on youtube. Just the drop in is amazing. Danny Way, a professional skater used this ramp to jump the Great Wall of China.
I'm afraid you haven't convinced me. Darts is no more a sport than chess or poker. It's a game. As for the pic: the guy looks to me as if he's posing to impress his girlfriend. By the way, I tried to upload a pic but kept getting an error message (file too big). I couldn't find what the size limit is.
I'm with you on the darts - and the pic was probably to impress a magazine editor or to earn photo royalties. As for impressing his boy/girl friend... he probably has better tricks than that! I copy and paste images straight into the text editor, if they're too big I paste into cloudup and grab the link. Haven't tried to do a straight upload in ages.