Don't have my old passports any longer, well, maybe.
I used to collect stamps and it seems you had to ask for a lot of them in Europe (they didn't bother).
So, I'll add my countries off memory and figure I had stamps for about 3/4 of them. I bought stamps and got a variety of money at every country I went to.
US (a freebie--was born there
)
Thailand
Japan
Taiwan
Phillipines
Viet Nam
Laos (don't ask)
Hong Kong (does that count...it wasn't actually China yet)
Germany
Austria
Italy
France
Spain
Switzerland
East Germany / East Berlin (when it was, well, communist)
Greece
Turkey
Belgium
Holland / Netherlands
England
Denmark
Sweeden
San Marino
Luxembourg
Andorra
Monaco
Liechtenstein
That should be about 25 (that's what I tell people but till now, I counted on my fingers).
[edit - looks more like 27 depending on if you allow some of them]