You can download Photofiltre for free, just Google it. I personally like it, and if you go on Youtube you can get tutorials on how to do really neat stuff.
A few features are crop, resize, and cut, copy and paste of course.
You can put text on the picture as well.
You can outline a shape then cut it and paste it on a new background, then blur the edges if you want. You may also use the 'clone stamp' which makes a duplicate of the outlined shape right in the same picture. You can revive colors, put the picture to grayscale, sepia, and many other tones. A really fun thing to do is try out the different textures. You can even convert the picture to make it look like a watercolor or sketch. There's much much more, so try it out.
There's also picnik.com but you can't do too much on it. Good luck!