Columnize is a little Go package that formats strings with separators into columns.
The standard Go log package is pretty barebones, but is fine for many simple programs. For more complex applications, though, you’d probably want to have different log levels for different events. There are many logging packages, such as the previously covered log15 that implement log leveling and provide other features. HashiCorp’s logutils is something different.
Go ships with
flag standard library package, which covers a lot of what’s needed to write command-line interfaces, however if you need more power and better structure for your console apps, try codegangsta’s package cli.go.
If you need to read Git repositories from Go, instead of calling
git command-line tool, consider using gogit.
Writing HTML document handling code with parsers is pretty hard. Even plain DOM tree walking can make your code look like spaghetti. That is why libraries like jQuery are popular: they make it easy to do queries and all sorts of other manipulations with HTML documents.
goquery is like jQuery, but in Go.
log15 is a powerful structured logging package for Go with a simple, easy-to-use API. It supports output with color when logging to terminal, and also can write to files, streams, syslog and network.