Any that would work with no money I guess, but it doesn't have to be limited to that. Idc what kind of coupon it is, its all relevant. If you have a folder full of them unsorted, you don't have to look through it or anything, you can just .rar it.
And to get free stuff. I mean games, drinks, drinks, electronics and those general areas would be cool, but any kind of coupon is fine.
Gimp or Photoshop could help.
I can't make coupons because I have have never messed with gimp or photoshop so I have no clue how to use it, but perhaps I could change a coupon if I had a guide.