Book 1 is shown here - it's a very useful book indeed for those in the early stages of learning, who want to get the basics of their technique in place in a methodical way. The other books are available via the IMSLP source link below.
This is a simple site, emulating a standard metronome. Very useful if you don't have access to a real one! It uses HTML5, so requires a fairly up-to-date browser.
Smartphone apps are another useful way to avoid buying dedicated devices. I use the free version of the gStrings chromatic tuner on an Android phone, and see there that the developer has also made a metronome widget...does anyone have similar recommendations for iPhone users?