The iPhone is something that with it's size and slick screen can easily slip out of your hands thus falling to the hard ground. Getting a hard shell case for it is nothing but a necessity. As soon as there is a crack in the iPhone it will completely void your warranty. Here are cases that will serve a protective purpose and keep your iPhone in good shape. For about $30 you can purchase the Incase protective cover for the iPhone. It has a nice grip outside but enough strength to protect from those drops (causes cracks and breaks) that are bound to happen. The Contour also has a grip case that is similar in price to the Incase cover and will do a great job protecting it as well.
The Apple universal dock is one of my favorite accessories to use with my iPhone. It may seem simple but it sure is nice to have a stand up dock for your iPhone. This dock works with not only iPhones but with the iPod too. With a slot for a power cord you can charge your iPhone as well as have it safely sitting up right in a secure dock. It's a little pricey as it runs about $49.
One of the biggest gripes that people had when the original iPhone was released and even today is the fingerprint issue on your touch screen. If it is not cleaned often then fingerprints can begin to take over the screen. A cure to that and to keep your screen in mint condition is to purchase this crystal film. It lays across the screen and will prevent fingerprints on your screen. It is easy to put on to the phone as well as remove it, leaving no marks on the screen. This is a must have if you're worried about fingerprints because though it may still develop on the shield, you can replace the film to maintain a spotless screen underneath. You can purchase two of these films for $14.95. On the apple website it says not compatible with iPhone 3G but there are others out there that will work. These may even work with a little tweaking as well but I would check with an Apple store to see what they have to say about it.
These accessories listed are just a few of the enormous variations. There are half a dozen different kinds of cases for the iPhone that serve similar purposes. They all run from about $20-$35 depending on the strength. Film for the screen is not something that will prevent the screen from breaking but it does protect from possible scratches and fingerprints. The dock accompanied with the remote gives a very stable stand for your iPhone to sit upright on. All of these are affordable and worth the buy. They will help preserve your iPhone's physical life by guarding against drops and other mishaps.