I found MetaFilter by way of Ask MetaFilter through Lifehackers weekly "Ask MetaFilter Round Up". I then signed up when I noticed my small town in a question about 2 years after lurking around it took me another year before I posted on MetaFilter.
The True News
My fondest memory of MetaFilter is always evolving. I would say MetaFilter is so important when big news breaks. When I see or hear about a huge news story (Earthquake in Japan, Osama Bin Laden Captured, ect.) MetaFilter is the first place that I come. I come straight here because the thread is updated so quickly with comments and insight as well as news links much quicker than news websites are. So I get all the information that I need faster and quicker than all news sources without the news channels politics.