I would use these to get myself on editors' radars.
I would use these to thank people who gave me the names of editors' radars that I should be on.
I would use these to thank the editors whose radars I got on and who gave me gigs after appearances on said radars.
I would use these to thank the people that bailed me out after I went bankrupt buying thank you cards.
And I would keep these for myself. Because they're awesome.