Additional Expenses

Memory Cards - about $50 to $150 for most people today. Memory costs are decreasing. See the Storage page.
Memory Card Reader - this costs about $25 and it is a very wise purchase. Do not kill your camera or its battery by downloading directly from the camera.
Spare Battery (+ keep it charged). Also note that rechargeable batteries can only be recharged so many times.
Image Editing Software - about $80 for most reasonable software packages. See the Image Editing page.
You may need to upgrade or purchase a new computer if you really get into this stuff. See the Computer Issues page.
Dazzle makes a $40 device to show slide shows on a TV. If you have a laptop computer with a S-Video output, simply get a S-Video cable and show a slide show on TV from your laptop. Both of these are great ways to show your friends, although the laptop-to-TV approach is the better of the two because you have more control and more horse-power.
A decent "Photo" printer - not simply a color printer. This is optional. For more info on printing, see the Making Prints page.
If you are in the middle of nowhere and do not have a laptop, then you can use a "Digital Wallet" to store 20GB in a small device that costs about $250. Digital wallets run on batteries and they are essentially a small portable hard drive. Some can store up to 80GB, but they cost more.