I love SimpleHTTPServer. I use it 80% of the time. One downside is that it's single-threaded, so if you have multiple people who need to fetch stuff from your server it can get pretty painful.
I was helping run a programming workshop last week and I wrote my own tiny concurrent server in Go but in the future I think I'll just use Caddy (https://github.com/mholt/caddy).
It can only serve one connection at a time, so if you're using it to serve a file download or have multiple users accessing it simultaneously it'll hang for all other clients.
It is faster to use an existing tool (python or another one) than rewriting a 2K LOC one. This is great for learning Go but the compounded time "lost" with a "slow" python server is nothing compared to the time this tool will require in development, debugging and maintenance over the years.
As anyone else, I am subject to NIH and I can understand why writing one's own library is interesting by itself. Please don't invent weak excuses like "ran is faster to type".
I was helping run a programming workshop last week and I wrote my own tiny concurrent server in Go but in the future I think I'll just use Caddy (https://github.com/mholt/caddy).