I am a pro photographer. I use photoshop but people frequently ask me this question! I recomend GIMP to everyone of them. If not picknic the photo editing software that you can get with flickr is good. I see you have a flickr I will check it out, if you are intrested mine is www.flickr.com/photos/gfryphotography my icon image is one I took this week
Happy snapping and I will take a look at your images and comment :)
Just thought I'd throw this out there to tell everybody features I want/need, etc.
1) Carve out focused object and put in different scenes.
2) Special effects like mist, cool letters, etc.
3) Different 'stickers' like birds (not cartoon), realistic stuff.