App/software to print this...

[smileyhappypeople]

I want to know what app or software or whatever people use to print things like this....
I don't actually want to make these, I just like the style of the writing etc for some other crafty bits but I've noticed quite a few people who sell crafty stuff use it so wondering if there is some fantastic app that does it for you?We have a Mac if that makes a difference?