Why didn't you use the .de ccTLD? Given that most German websites are not using .com domains, isn't this potentially confusing, and causing you to lose traffic? You don't even own thinks.de; it's blank.
For one othing, .com stands for "commercial". .us is for USA.
Regarding whether it's right to do so or not is another question. For starters, it depends on the regulations of each country, as in some of them you simply are not allowed to operate under a different TLD. But most countries are not this restrictive.
One of the many things that were supposed to "make sense" at the dawn of the web, and that were quickly abused and evolved into more than what anyone could possibly have thought of at first. (No, no, I'm not thinking of HTTP at all while writing this. Why would I?)
If you mostly frequent English sites, that's not surprising, but in reality many .com sites are not in English. Some reasons include restrictive ccTLD rules (for example, until 2012 you couldn't register a .pt domain, only .com.pt/.org.pt/etc), better recognition of the TLD by users and SEO.
Some examples from the top 200 sites: http://baidu.com, http://qq.com, http://taobao.com, http://sohu.com, http://naver.com, http://coccoc.com, http://globo.com
In my country, the ccTLD costs more than double the .com equivalent, and requires manual intervention to set up. I have to wait for a guy (and it's just one guy who's been handling it for over a decade) to show up for work on Monday, go through his emails, finish his coffee, and then manually set up my DNS.
Given the above, .com's are always the first choice.