Now Photoshop is an amazing software, but it is expensive and it is very much focusing on full-time designers that really get into all its complicated features.
If you only use pictures from time to time and you only go for basic functions like color adjustments, resizing images and so on, the free an very user friendly Irfanview will be the photo-imaging-editor for you.
However if you are looking for just this bit more, Sumo Paint will most likely give you all the features you are looking for... and more. Sumo Paint is a browser application and it has 2.0 features, so it offers many of the contemporary features you expect as a member of the cloud.
Lockergnome just released a video on Sumo Paint in collaboration with techoverloads and it gives you a five minute quick overall view of its possibilities... nice!