5 years ago today SallyC and I completed the Oregon DeLorme Challenge. It still ranks as the top accomplishment of my geocaching career. Days of big numbers can't compare to those 77 caches.
I'm a big fan of challenge caches and feel they should have there own icon. Though personally I find it hard to compare say the ABC Challenge to those like the DeLorme or CCIO. I guess just like caches there is a challenge for everybody.