A GIF decoder: an exercise in Go interfaces
blog.golang.org
blog.golang.org
It's a nice write-up, but I'm not sure it shows off anything particular to Go.
In any case, this post was written to educate Go programmers, and not (primarily) to evangelize Go.
Also, the slice backed by inline array is a pretty great thing. It's cache-friendly, avoids extra allocations, and is pretty easy to use safely. Aside from D, I don't know of any other usable garbage-collected languages that can do this so nicely.