The iMac's chassis is strictly desktop -- there are no holes for a VESA wall or articulating arm mount. The chassis is balanced on an elegant, one-piece aluminum easel that lets you tilt or rotate the display with one hand. Instead of using sticky rubber feet, the easel has a skid pad that lets you move the iMac easily, but not too easily, around your desk. There is no height adjustment, but the tilt angle range is broad enough to give you a straight-line view from anywhere. And for those times when you need to move the iMac to another room, say, to give a presentation, it's readily luggable, and its one-wire design makes relocation a snap.
If you do need another display (or two, if you have a 27-inch iMac), you can plug a mini DisplayPort to DVI or HDMI adapter into the Thunderbolt port. For resolutions beyond 1080p, make sure you buy a dual-link DVI adapter. When you're planning your iMac system, you can think of the built-in display as your primary or secondary monitor. Your monitor preference kicks in after OS X finishes booting.
When you go online to buy your iMac, you're offered a couple of simple but important choices. The standard keyboard and pointing device are Bluetooth-based and first-rate. The keyboard is a compact layout (the keys are full size) that's familiar to Apple notebook users. If you prefer a full keyboard with a numeric keypad and function keys up to F19, it won't cost you any money, but it will connect via USB. You can't lose either way; Apple's keyboards have the sweetest feel. If you're a keyboard connoisseur, go ahead and sample aftermarket alternatives. You'll come back to Apple.
As with the keyboard, Apple lets you choose between two pointing devices. Here, I implore you to set aside any presumed preference for a mouse, which is what you get by default, in favor of Apple's Magic Trackpad. The touch-sensitive top of the Magic Mouse provides only a small subset of OS X's multitouch experience. While you can get around just fine in Snow Leopard with a mouse, Lion is all about touch.
Once you drop your prejudice and make the switch, you'll discover that Magic Trackpad is brilliantly engineered. It's much larger than a notebook trackpad, yet takes up less desk space than a mousepad. Your fingertips glide across the smooth glass surface, making multitouch gestures -- and noiseless left and right clicks without buttons -- feel natural. Once you try it, you'll be hooked. Magic Trackpad is the only way to drive any Mac.