We automatically add popular domain name beginnings and endings to whatever you type in the search box. Sometimes we will show a generated name as available when it’s really not. This is because we check domain availability by looking it up in the zone file. We can do this instantly because we store the zone files on our servers in a very efficient way.
I agree with you that Pulse CMS offers an interesting way to go, without databases. Before moving all my sites to WP over the past two years, I had always felt reluctant to use databases: but testing WP had convinced me to go ahead. Although I do not use it at this point (I played a little bit with previous versions), I bought a Pulse CMS license, if only in order to support that interesting project. I do not rule out using it for a site some day, at least experimentally.