Website or APP to let me Arrange images in a rectangle

I am looking for a website and/or app that lets me arrange a set of images (JPEGs) in a rectangle then creates one big rectangle of the display. For example, I want to arrange 6 images in a rectangle 2 wide by 3 tall. I input the images numbered 1 to 6 and it displays them like this:

1 2
3 4
5 6

Then I decide to switch 1 and 4:

4 2
3 1
5 6

Switch row 1 and 3:

5 6
3 1
4 2

Add more horizontal space:

5 . 6
3 . 1
4 . 2

Then I have it download the image.

1. How many websites do you know that do this?
2. How many websites do only this (or only this on one page)?
3. How many apps do you know that do this?
4. How many apps do only this (or only this on one display)?
Price for each?

I will pay you for each one you show me.