http://golang.org/pkg/net/http/#FileServer

go-serve-folder.go

package main                                                                                                                                        

import (                                                                                                                                            
  "fmt"                                                                                                                                           
  "log"                                                                                                                                           
  "flag"                                                                                                                                          

  "net/http"                                                                                                                                      
)                                                                                                                                                   

var (                                                                                                                                               
  port int                                                                                                                                        
  folder string                                                                                                                                   
)                                                                                                                                                   

func init() {                                                                                                                                       
  flag.IntVar(&port, "port", 8080, "HTTP Server Port")                                                                                            
  flag.StringVar(&folder, "folder", "www", "Serve this folder")                                                                                   

  flag.Parse()                                                                                                                                    
}                                                                                                                                                   

func main() {                                                                                                                                       
  httpAddr := fmt.Sprintf(":%v", port)                                                                                                            

  log.Printf("Listening to %v", httpAddr)                                                                                                         

  // http://golang.org/pkg/net/http/#FileServer
  http.Handle("/statics/", http.StripPrefix("/statics/", http.FileServer(http.Dir(folder))))                                                      
  log.Fatal(http.ListenAndServe(httpAddr, nil))                                                                                                   
}

Nice and clean, thank you