Sometimes AMEX has offers in Europe. I was in Vienna a couple of weeks back and at a sales desk in the airport they offered 30.000 MR points after 3.000€ spent in 3 months.

Only requirement has been to have an Austrian or German bank account. Did sign up, and received the signup bonus after hitting the 3k.

Later on I looked up the offer on the website but couldn't find any reference to it, so it seems the direct sales can offer sometimes signup bonuses you won't find published online.

The German HHonors Visa credited measly 10.000 points signups bonus after the first stay. Same requirement - having a German bank account but in addition for opening the card you need to prove you identify. They use PostIdent which you can only do in post offices in Germany or through a legal entity confirming your identity which could be quite a hassle living abroad. By accident I was connecting in Germany anyway and just handed in the PostIdent at the post office in the airport.

Anyway, signup bonuses in Germany or Austria are rare and certainly not in the extend of what you are used to in the US.