I hate to break it to you kiddo, but the most popular porno site names are very taken. I strongly recommend you to go to Domain or another domain name buying site and enter names. It will give you a list of suggested and available domains that start with .com.
True story on this topic... back in 1999 when I was studying web design my instructor told the class that a few years earlier one of the other instructors was teaching an intro to the internet course for a group from a senior citizen's center and wanted to take them to the web site for the White House. Simple, right? So he told them to type in Whitehouse.com only to find from the gasp of the older women and the cheers from the older men that it was a website for a strip club called "The White House".
In terms of the original question, I would not limit your search to '.com' only. You will find that your options are greater and if it is a really good site people will remember you name regardless of if it is .com, .us, etc.
Oh that is so funny. But not to be a devil's advocate, but most companies prefer a .com because you hardly ever see a .com on the search engine result pages, with the exception of .gov, .edu, and .org.