13th month in archives

What I am looking for is a method to have my archives displayed as

January 2007
February 2007
.
.
.
December 2007
Older

In other words, I need a thirteenth ‘month’ in my sidebar under which all spillover (messages older than 12 months) will be collected. So last 12 months (rolling over as WP has it now) and a collective dump for the older stuff.

Is this doable? Has anyone seen something like that?

Thanks for your input,

Ray

PS: https://www.haze.ch and you see why I ask.