I frequently use Picasa3.6 to edit images.Specially to make excellent quality thumbnail image of any size. This software is free and easy to use.Some simple image editing can be done with this efficiently.Nodoubt adobe Photoshop is much professional,but it requires some time to understand its function.
With Picasa3.6 you can do lots of image editing but one thing I do mainly is to resize and crop image and upload it directly.This helps my web developement and have to appreciate that the quality of resized image is excellent.And I don't have to find images,picasa automatically scans computer to find images and shows them folderwise.When you add or download image,picasa quickly update this new addition,also it can update any edit of images while it is running.
Picasa3.6-Its a free software from google.You can download this from google.
Some cool options in picasa-
Thumbnail Image can be made easily of any size.You can make thumbnail of an image 1280/900 px,300kb to 50/30px,2kb. The quality remains intact.
Can put watermark on images easily.
Can make cool picture collages.
Crop image easily.
Some simple image perfection tools.
Can write text on images digitally,and the image quality remains intact.
Upload images directly to web.
This simple features I mostly use.Well there are lots of more features in Picasa,why don't you find them.
One thing-I don't know if you already know,if you have a gmail account,you can have a free 1GigaByte image hosting in Picasa web.Then with picasa3.6 you can directly upoad image from your computer to picasa web.
Get this free image Hosting from google
You can also try for microsoft office picture manager.The quality is not good,but I use it to crop images.You can crop image in pixel wise with this program.
If you have microsoft office installed,Goto start>all program,microsoft office>microsoft office tools>microsoft office picture picture manager.