Partslink24.com (Web ETKA/ETOS for US)
Most people probably know this already... it's a Web site run by LexCom GmbH, the maker of ETKA. Registration for US users on Partslink24.com is free, but there is a catch.
I registered and got a login, but I couldn't browse the parts catalog until I added a credit card number. To make sure I wouldn't get charged, I generated a Virtual Account Number with my Citi card, allowed it $2 max, and entered it in my account info. Good to go, and a few weeks later, no charge has yet to appear (I closed the virtual number a day later). I registered back in Jan and my account is good until August - who knows what would happen then. I like the Web version because I can access it from just about any computer with Java installed.