We keep technical version names, similar to earlier described, using the iteration number as the main digit.
For customers, we apply project-specific release names, part of a consecutive set. For a recent gig we named the releases after the consecutive runners up of the (Dutch version of) the TV talent show America's Next Top Model. The first iteration released "Kathelijn" (ended in 10th place), next we released "Stefanie" (ended 9th).
We like to be creative at this, we maintain the natural order in the naming. You have to name all future iterations from day 1 to do this.
Another option is to name the release after the most prominent feature it brings. E.g "One-click to order" and the "Basic reporting".
Naming is important, a catchy name is worth a lot, even for an iteration.
PS. Google Sets can help you think of the next...