Check if your doman names can be taken.
It's very easy. Just install ruby and run commands like below.
$ bundle
$ cp top_level.conf.sample top_level.conf
Just run checkdomain command with domain name which you want to take.
$ ./checkdomain domainname
$ checkdomain yoshihirosawa
yoshihirosawa.com: already exists.
yoshihirosawa.net: can be taken!
yoshihirosawa.co.jp: can be taken!
yoshihirosawa.jp: can be taken!
yoshihirosawa.info: can be taken!
yoshihirosawa.mobi: can be taken!