Even though I knew about Instagram for a while, I didn't really get excited about it until I wanted to use it for sharing pictures while on my trip to Germany this past September. Once I started using it, I really got the bug.
Now the Instagram developers have made sharing images even easier by creating a web interface for each registered user of the app. So I can point anyone, even my mom, to this page so they can follow along as I document the things that catch my eye on a daily basis.
For me, Instagram is like a visual Twitter. I can capture one image that tells the story of something I experienced or saw that day. And like Twitter, I enjoy looking at the images by others just as much as I do creating my own.