Don't be a bandwidth hog
Digital image files can be huge. An image created with a tiny 10-megapixel camera is often 3.5MB or larger.
That's great for a wall-sized print. But when you plan to send an image by e-mail, blog it, or publish it on the web, reducing the image resolution (and thereby reducing the file size) is a must.
If you use any flavor of Adobe Photoshop, open the image and select Image Size from the drop-down menu. Set the horizontal resolution to 800 and save the file under a new name. (Be careful! If you fail to rename the file you may lose the original size and resolution forever.)
Don't have Photoshop? Windows XP Resize Power Toy is a free application that lets Windows users right-click an image with your mouse and select the new resolution from a drop-down menu. You can even resize several images at once. The original image is not altered; instead, a new, smaller image is created and saved under a new name.
This shot of a red caboose, taken with a 10-megapixel Casio EX Z1050, was 5.5MB before I resized it to more manageable 180KB VGA (640x480) image. (Final version shown here is 450x338 pixels and--44KB.)