There are a ton of websites to have fun with and learn typography at the same time. There are also several very cool apps that let you take the fun on the go. Great for when you have time to waste.
LetterMPress gives you a virtual letterpress on your iPad. Design your own composition from vintage wood type, ink your press and then hand crank to make your print.
If you want more options and a simpler set up try SimplyMPress, from the same folks that made LetterMPress.
You need this! WhatTheFont let’s you identify any font, any where, right on your phone.
Typography Insight is perfect if you’re just starting to learn about typography.
The Typography Manual
The Typography Manual is packed with useful resources for designers, including a type anatomy glossary, a font size ruler, an em calculator, style guide, HTML character codes and more!
Type:Rider is a beautiful interactive game that helps you discover the history of typography.
Those are my favorites, what are yours?