I consider myself left-handed, primarily because I write with my left hand, but really I'm just a mess.
Write left
"One handed" sports (tennis, ping pong, racquetball, bowling, etc.) - lefty
"Two handed" sports (hockey, golf, etc.) - righty
Throw - lefty
Catch (baseball/softball glove) with my right EXCEPT when playing hockey goalie, in which case I catch with my left hand and hold stick in my right hand
Eat - fork in left hand (and keep in in left hand when cutting with a knife)
Computer mouse - use right hand