To my understanding there have been a few key moments in game where people have amassed huge sums of money, or created very valuable items. I'll start the list, but I'm sure there are plenty more going back in the history of guild wars.
1. that fateful day when all material prices were reset to 100g. I wish I could have been there. (I'm thinking this is #1 for guys with riches comin out of their ears)

2. invention of the 55 monk and solo farming in the early days
3. farming greens when they first came out in sorrows furnace
4. invention of the droks run!! though i don't know the prices it started off at
5. bringing back post-sear items to pre
6. grinding it out 2 man style in FoW for months on end.
7. finding a titan gem from domain of anguish
8. finding a crystalline sword
9. finding an elemental sword
what else can you add?
