http://tour.golang.org/

An interactive introduction to Go in three sections. The first section covers basic syntax and data structures; the second discusses methods and interfaces; and the third introduces Go's concurrency primitives. Each section concludes with a few exercises so you can practice what you've learned.

Exercise: Loops and Functions
http://tour.golang.org/#23

Exercise: Slices
http://tour.golang.org/#35

Exercise: Maps
http://tour.golang.org/#40

Exercise: Fibonacci closure
http://tour.golang.org/#43

Advanced Exercise: Complex cube roots
http://tour.golang.org/#47

Exercise: Errors
http://tour.golang.org/#55

Exercise: HTTP Handlers
http://tour.golang.org/#57

Exercise: Images
http://tour.golang.org/#59

Exercise: Rot13 Reader
http://tour.golang.org/#60

Exercise: Equivalent Binary Trees
http://tour.golang.org/#68

Exercise: Web Crawler
http://tour.golang.org/#70