I had a quick look at the AmEx Austria page and didn't see any sign up bonuses on any of the cards. I'd recommend looking at each of the main banks websites and doing the same, if you do find any cards with a sign up bonus then you can start looking for blogs/communities to see what the best Austrian offers are.

I think this is a pretty interesting, so I'll likely do a series of blogposts on this (although probably not on Austria as I imagine there aren't a lot of you out there).