CED Pro
It's because (in my case) we're too damned lazy to find a stamp.
I've purchased a couple of thousand dollars (hmmm, probably a lot more now
that I think of it) of Amiga software. The only registration cards I've
sent in were for Aztec, AREXX, and WShell. CEDPro's registration is all
filled out — will mail it when I find a stamp. Probably a couple of
months after WB 1.4 comes out.