You’ve probably already seen this photo photo with the caption "no, I did not photoshop this" but gizmodo, the bible for those with the must have shiny toys, give proof that it was photoshoped. Which brings me to the point that the easiest way to improve your digital photos is via cropping and you don’t need expensive photo editing software, like photoshop, to be able to achieve that.
Picasa from google is free to download, and works on both windows & apple mac, has an easy to use and nicely visual crop tools. So does Windows Live Photogallery and gimp. So no need to fork out a small fortune to start improving your photos.
There are also now many on-line photo editors,like Picnik, which is available to edit within flickr & facebook. A new kid on the block is Aviary, which is written in flash and thus a little slower. The cropping is part of the Phoenix image editor. However it is an amazing full featured suite for a free on-line tool. So go get creative.