The problem with the Raspberry Pi is that it doesn't come with a keyboard, mouse and monitor so you can use it as a computer. Adafruit solves most of that with the Computer Add-On Pack.
Included here is a wired keyboard, wired mouse and HDMI cable, all for $US23. It's not exactly the best stuff on the market, but if you just want to get started using a Raspberry Pi, it's handy to have everything you need in one pack. Everything is verified to work with the Pi, doesn't require any setup (except plugging them in), and it's cheap enough that it's worth it even if you already have this stuff around just so you can get a dedicated setup for your Pi.
Computer Add-On Pack for Raspberry Pi ($US22.95) [Adafruit]