I seem to recall seeing somewhere that there was some travelers´s health coverage with certain credit cards. True or am I imagining that?

In australia, master card includes some travelers insurance, but you have to verify what it covers

Ok... but nothing like that in the US?

Some do, you'll have to check your card company and it may only be if you use their card to finance part of your trip. Check your regular medical insurance as well, they may cover some things when traveling also.