I remember seeing these as a kid... always wanted to catch one...
http://www.travelafricamag.com/content/view/745/72/
They fish them with flies and steel leaders...
http://www.karibahouseboats.com/images/fish/t2lg.jpg
http://www.rackelhanen.se/eng/10216.htm
Other than that... I really want to catch an alligator gar. Love Butt and salmon. Would love to hook into a monster southern smallmouth. Would love to try kite fishing. But not from a kayak...
http://www.fishingkites.co.nz/sharks...arkattack.html
'cuda, marlin... so many fish and really, really little time...