For the people flaming saying "Gambits are stupid", "you shouldn't play this or that", this isn't your thread (weaknesses to watch out for is acceptable).

I want to know some ideas of what to play in games where I can throw a pawn away in an opening and let it show advantage, and I have found lines for every situation except when playing against a king pawn opening.

The openings I've been looking at:

You should not play the Latvian Gambit unless you like to defend a pawn down endgame without compensation.

The phrase "throw a pawn away" says it all. An opening gambit isn't "throwing a pawn away." Agitation for the sake of agitation isn't intelligent chess playing. Just make good, solid moves until White makes a bad move. Otherwise, the game's a draw, and that's OK too.

Basically, anything below master is playable. And the shorter the time control, pretty much anything can go.